| /* |
| * Resizable virtual memory filesystem for Linux. |
| * |
| * Copyright (C) 2000 Linus Torvalds. |
| * 2000 Transmeta Corp. |
| * 2000-2001 Christoph Rohland |
| * 2000-2001 SAP AG |
| * 2002 Red Hat Inc. |
| * Copyright (C) 2002-2011 Hugh Dickins. |
| * Copyright (C) 2011 Google Inc. |
| * Copyright (C) 2002-2005 VERITAS Software Corporation. |
| * Copyright (C) 2004 Andi Kleen, SuSE Labs |
| * |
| * Extended attribute support for tmpfs: |
| * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> |
| * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
| * |
| * tiny-shmem: |
| * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #include <linux/fs.h> |
| #include <linux/init.h> |
| #include <linux/vfs.h> |
| #include <linux/mount.h> |
| #include <linux/ramfs.h> |
| #include <linux/pagemap.h> |
| #include <linux/file.h> |
| #include <linux/mm.h> |
| #include <linux/export.h> |
| #include <linux/swap.h> |
| #include <linux/aio.h> |
| |
| static struct vfsmount *shm_mnt; |
| |
| #ifdef CONFIG_SHMEM |
| /* |
| * This virtual memory filesystem is heavily based on the ramfs. It |
| * extends ramfs by the ability to use swap and honor resource limits |
| * which makes it a completely usable filesystem. |
| */ |
| |
| #include <linux/xattr.h> |
| #include <linux/exportfs.h> |
| #include <linux/posix_acl.h> |
| #include <linux/posix_acl_xattr.h> |
| #include <linux/mman.h> |
| #include <linux/string.h> |
| #include <linux/slab.h> |
| #include <linux/backing-dev.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/writeback.h> |
| #include <linux/blkdev.h> |
| #include <linux/pagevec.h> |
| #include <linux/percpu_counter.h> |
| #include <linux/falloc.h> |
| #include <linux/splice.h> |
| #include <linux/security.h> |
| #include <linux/swapops.h> |
| #include <linux/mempolicy.h> |
| #include <linux/namei.h> |
| #include <linux/ctype.h> |
| #include <linux/migrate.h> |
| #include <linux/highmem.h> |
| #include <linux/seq_file.h> |
| #include <linux/magic.h> |
| |
| #include <asm/uaccess.h> |
| #include <asm/pgtable.h> |
| |
| #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
| #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
| |
| /* Pretend that each entry is of this size in directory's i_size */ |
| #define BOGO_DIRENT_SIZE 20 |
| |
| /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ |
| #define SHORT_SYMLINK_LEN 128 |
| |
| /* |
| * shmem_fallocate and shmem_writepage communicate via inode->i_private |
| * (with i_mutex making sure that it has only one user at a time): |
| * we would prefer not to enlarge the shmem inode just for that. |
| */ |
| struct shmem_falloc { |
| pgoff_t start; /* start of range currently being fallocated */ |
| pgoff_t next; /* the next page offset to be fallocated */ |
| pgoff_t nr_falloced; /* how many new pages have been fallocated */ |
| pgoff_t nr_unswapped; /* how often writepage refused to swap out */ |
| }; |
| |
| /* Flag allocation requirements to shmem_getpage */ |
| enum sgp_type { |
| SGP_READ, /* don't exceed i_size, don't allocate page */ |
| SGP_CACHE, /* don't exceed i_size, may allocate page */ |
| SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ |
| SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ |
| SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ |
| }; |
| |
| #ifdef CONFIG_TMPFS |
| static unsigned long shmem_default_max_blocks(void) |
| { |
| return totalram_pages / 2; |
| } |
| |
| static unsigned long shmem_default_max_inodes(void) |
| { |
| return min(totalram_pages - totalhigh_pages, totalram_pages / 2); |
| } |
| #endif |
| |
| static bool shmem_should_replace_page(struct page *page, gfp_t gfp); |
| static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index); |
| static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); |
| |
| static inline int shmem_getpage(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, int *fault_type) |
| { |
| return shmem_getpage_gfp(inode, index, pagep, sgp, |
| mapping_gfp_mask(inode->i_mapping), fault_type); |
| } |
| |
| static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
| { |
| return sb->s_fs_info; |
| } |
| |
| /* |
| * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
| * for shared memory and for shared anonymous (/dev/zero) mappings |
| * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
| * consistent with the pre-accounting of private mappings ... |
| */ |
| static inline int shmem_acct_size(unsigned long flags, loff_t size) |
| { |
| return (flags & VM_NORESERVE) ? |
| 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); |
| } |
| |
| static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
| { |
| if (!(flags & VM_NORESERVE)) |
| vm_unacct_memory(VM_ACCT(size)); |
| } |
| |
| /* |
| * ... whereas tmpfs objects are accounted incrementally as |
| * pages are allocated, in order to allow huge sparse files. |
| * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
| * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
| */ |
| static inline int shmem_acct_block(unsigned long flags) |
| { |
| return (flags & VM_NORESERVE) ? |
| security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; |
| } |
| |
| static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
| { |
| if (flags & VM_NORESERVE) |
| vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); |
| } |
| |
| static const struct super_operations shmem_ops; |
| static const struct address_space_operations shmem_aops; |
| static const struct file_operations shmem_file_operations; |
| static const struct inode_operations shmem_inode_operations; |
| static const struct inode_operations shmem_dir_inode_operations; |
| static const struct inode_operations shmem_special_inode_operations; |
| static const struct vm_operations_struct shmem_vm_ops; |
| |
| static struct backing_dev_info shmem_backing_dev_info __read_mostly = { |
| .ra_pages = 0, /* No readahead */ |
| .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, |
| }; |
| |
| static LIST_HEAD(shmem_swaplist); |
| static DEFINE_MUTEX(shmem_swaplist_mutex); |
| |
| static int shmem_reserve_inode(struct super_block *sb) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| if (sbinfo->max_inodes) { |
| spin_lock(&sbinfo->stat_lock); |
| if (!sbinfo->free_inodes) { |
| spin_unlock(&sbinfo->stat_lock); |
| return -ENOSPC; |
| } |
| sbinfo->free_inodes--; |
| spin_unlock(&sbinfo->stat_lock); |
| } |
| return 0; |
| } |
| |
| static void shmem_free_inode(struct super_block *sb) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| if (sbinfo->max_inodes) { |
| spin_lock(&sbinfo->stat_lock); |
| sbinfo->free_inodes++; |
| spin_unlock(&sbinfo->stat_lock); |
| } |
| } |
| |
| /** |
| * shmem_recalc_inode - recalculate the block usage of an inode |
| * @inode: inode to recalc |
| * |
| * We have to calculate the free blocks since the mm can drop |
| * undirtied hole pages behind our back. |
| * |
| * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
| * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
| * |
| * It has to be called with the spinlock held. |
| */ |
| static void shmem_recalc_inode(struct inode *inode) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| long freed; |
| |
| freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
| if (freed > 0) { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| if (sbinfo->max_blocks) |
| percpu_counter_add(&sbinfo->used_blocks, -freed); |
| info->alloced -= freed; |
| inode->i_blocks -= freed * BLOCKS_PER_PAGE; |
| shmem_unacct_blocks(info->flags, freed); |
| } |
| } |
| |
| /* |
| * Replace item expected in radix tree by a new item, while holding tree lock. |
| */ |
| static int shmem_radix_tree_replace(struct address_space *mapping, |
| pgoff_t index, void *expected, void *replacement) |
| { |
| void **pslot; |
| void *item = NULL; |
| |
| VM_BUG_ON(!expected); |
| pslot = radix_tree_lookup_slot(&mapping->page_tree, index); |
| if (pslot) |
| item = radix_tree_deref_slot_protected(pslot, |
| &mapping->tree_lock); |
| if (item != expected) |
| return -ENOENT; |
| if (replacement) |
| radix_tree_replace_slot(pslot, replacement); |
| else |
| radix_tree_delete(&mapping->page_tree, index); |
| return 0; |
| } |
| |
| /* |
| * Sometimes, before we decide whether to proceed or to fail, we must check |
| * that an entry was not already brought back from swap by a racing thread. |
| * |
| * Checking page is not enough: by the time a SwapCache page is locked, it |
| * might be reused, and again be SwapCache, using the same swap as before. |
| */ |
| static bool shmem_confirm_swap(struct address_space *mapping, |
| pgoff_t index, swp_entry_t swap) |
| { |
| void *item; |
| |
| rcu_read_lock(); |
| item = radix_tree_lookup(&mapping->page_tree, index); |
| rcu_read_unlock(); |
| return item == swp_to_radix_entry(swap); |
| } |
| |
| /* |
| * Like add_to_page_cache_locked, but error if expected item has gone. |
| */ |
| static int shmem_add_to_page_cache(struct page *page, |
| struct address_space *mapping, |
| pgoff_t index, gfp_t gfp, void *expected) |
| { |
| int error; |
| |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| VM_BUG_ON_PAGE(!PageSwapBacked(page), page); |
| |
| page_cache_get(page); |
| page->mapping = mapping; |
| page->index = index; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| if (!expected) |
| error = radix_tree_insert(&mapping->page_tree, index, page); |
| else |
| error = shmem_radix_tree_replace(mapping, index, expected, |
| page); |
| if (!error) { |
| mapping->nrpages++; |
| __inc_zone_page_state(page, NR_FILE_PAGES); |
| __inc_zone_page_state(page, NR_SHMEM); |
| spin_unlock_irq(&mapping->tree_lock); |
| } else { |
| page->mapping = NULL; |
| spin_unlock_irq(&mapping->tree_lock); |
| page_cache_release(page); |
| } |
| return error; |
| } |
| |
| /* |
| * Like delete_from_page_cache, but substitutes swap for page. |
| */ |
| static void shmem_delete_from_page_cache(struct page *page, void *radswap) |
| { |
| struct address_space *mapping = page->mapping; |
| int error; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| error = shmem_radix_tree_replace(mapping, page->index, page, radswap); |
| page->mapping = NULL; |
| mapping->nrpages--; |
| __dec_zone_page_state(page, NR_FILE_PAGES); |
| __dec_zone_page_state(page, NR_SHMEM); |
| spin_unlock_irq(&mapping->tree_lock); |
| page_cache_release(page); |
| BUG_ON(error); |
| } |
| |
| /* |
| * Like find_get_pages, but collecting swap entries as well as pages. |
| */ |
| static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping, |
| pgoff_t start, unsigned int nr_pages, |
| struct page **pages, pgoff_t *indices) |
| { |
| void **slot; |
| unsigned int ret = 0; |
| struct radix_tree_iter iter; |
| |
| if (!nr_pages) |
| return 0; |
| |
| rcu_read_lock(); |
| restart: |
| radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { |
| struct page *page; |
| repeat: |
| page = radix_tree_deref_slot(slot); |
| if (unlikely(!page)) |
| continue; |
| if (radix_tree_exception(page)) { |
| if (radix_tree_deref_retry(page)) |
| goto restart; |
| /* |
| * Otherwise, we must be storing a swap entry |
| * here as an exceptional entry: so return it |
| * without attempting to raise page count. |
| */ |
| goto export; |
| } |
| if (!page_cache_get_speculative(page)) |
| goto repeat; |
| |
| /* Has the page moved? */ |
| if (unlikely(page != *slot)) { |
| page_cache_release(page); |
| goto repeat; |
| } |
| export: |
| indices[ret] = iter.index; |
| pages[ret] = page; |
| if (++ret == nr_pages) |
| break; |
| } |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| /* |
| * Remove swap entry from radix tree, free the swap and its page cache. |
| */ |
| static int shmem_free_swap(struct address_space *mapping, |
| pgoff_t index, void *radswap) |
| { |
| int error; |
| |
| spin_lock_irq(&mapping->tree_lock); |
| error = shmem_radix_tree_replace(mapping, index, radswap, NULL); |
| spin_unlock_irq(&mapping->tree_lock); |
| if (!error) |
| free_swap_and_cache(radix_to_swp_entry(radswap)); |
| return error; |
| } |
| |
| /* |
| * Pagevec may contain swap entries, so shuffle up pages before releasing. |
| */ |
| static void shmem_deswap_pagevec(struct pagevec *pvec) |
| { |
| int i, j; |
| |
| for (i = 0, j = 0; i < pagevec_count(pvec); i++) { |
| struct page *page = pvec->pages[i]; |
| if (!radix_tree_exceptional_entry(page)) |
| pvec->pages[j++] = page; |
| } |
| pvec->nr = j; |
| } |
| |
| /* |
| * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. |
| */ |
| void shmem_unlock_mapping(struct address_space *mapping) |
| { |
| struct pagevec pvec; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| pgoff_t index = 0; |
| |
| pagevec_init(&pvec, 0); |
| /* |
| * Minor point, but we might as well stop if someone else SHM_LOCKs it. |
| */ |
| while (!mapping_unevictable(mapping)) { |
| /* |
| * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it |
| * has finished, if it hits a row of PAGEVEC_SIZE swap entries. |
| */ |
| pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
| PAGEVEC_SIZE, pvec.pages, indices); |
| if (!pvec.nr) |
| break; |
| index = indices[pvec.nr - 1] + 1; |
| shmem_deswap_pagevec(&pvec); |
| check_move_unevictable_pages(pvec.pages, pvec.nr); |
| pagevec_release(&pvec); |
| cond_resched(); |
| } |
| } |
| |
| /* |
| * Remove range of pages and swap entries from radix tree, and free them. |
| * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. |
| */ |
| static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, |
| bool unfalloc) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; |
| unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); |
| unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); |
| struct pagevec pvec; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| long nr_swaps_freed = 0; |
| pgoff_t index; |
| int i; |
| |
| if (lend == -1) |
| end = -1; /* unsigned, so actually very big */ |
| |
| pagevec_init(&pvec, 0); |
| index = start; |
| while (index < end) { |
| pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE), |
| pvec.pages, indices); |
| if (!pvec.nr) |
| break; |
| mem_cgroup_uncharge_start(); |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| index = indices[i]; |
| if (index >= end) |
| break; |
| |
| if (radix_tree_exceptional_entry(page)) { |
| if (unfalloc) |
| continue; |
| nr_swaps_freed += !shmem_free_swap(mapping, |
| index, page); |
| continue; |
| } |
| |
| if (!trylock_page(page)) |
| continue; |
| if (!unfalloc || !PageUptodate(page)) { |
| if (page->mapping == mapping) { |
| VM_BUG_ON_PAGE(PageWriteback(page), page); |
| truncate_inode_page(mapping, page); |
| } |
| } |
| unlock_page(page); |
| } |
| shmem_deswap_pagevec(&pvec); |
| pagevec_release(&pvec); |
| mem_cgroup_uncharge_end(); |
| cond_resched(); |
| index++; |
| } |
| |
| if (partial_start) { |
| struct page *page = NULL; |
| shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); |
| if (page) { |
| unsigned int top = PAGE_CACHE_SIZE; |
| if (start > end) { |
| top = partial_end; |
| partial_end = 0; |
| } |
| zero_user_segment(page, partial_start, top); |
| set_page_dirty(page); |
| unlock_page(page); |
| page_cache_release(page); |
| } |
| } |
| if (partial_end) { |
| struct page *page = NULL; |
| shmem_getpage(inode, end, &page, SGP_READ, NULL); |
| if (page) { |
| zero_user_segment(page, 0, partial_end); |
| set_page_dirty(page); |
| unlock_page(page); |
| page_cache_release(page); |
| } |
| } |
| if (start >= end) |
| return; |
| |
| index = start; |
| for ( ; ; ) { |
| cond_resched(); |
| pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE), |
| pvec.pages, indices); |
| if (!pvec.nr) { |
| if (index == start || unfalloc) |
| break; |
| index = start; |
| continue; |
| } |
| if ((index == start || unfalloc) && indices[0] >= end) { |
| shmem_deswap_pagevec(&pvec); |
| pagevec_release(&pvec); |
| break; |
| } |
| mem_cgroup_uncharge_start(); |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| index = indices[i]; |
| if (index >= end) |
| break; |
| |
| if (radix_tree_exceptional_entry(page)) { |
| if (unfalloc) |
| continue; |
| nr_swaps_freed += !shmem_free_swap(mapping, |
| index, page); |
| continue; |
| } |
| |
| lock_page(page); |
| if (!unfalloc || !PageUptodate(page)) { |
| if (page->mapping == mapping) { |
| VM_BUG_ON_PAGE(PageWriteback(page), page); |
| truncate_inode_page(mapping, page); |
| } |
| } |
| unlock_page(page); |
| } |
| shmem_deswap_pagevec(&pvec); |
| pagevec_release(&pvec); |
| mem_cgroup_uncharge_end(); |
| index++; |
| } |
| |
| spin_lock(&info->lock); |
| info->swapped -= nr_swaps_freed; |
| shmem_recalc_inode(inode); |
| spin_unlock(&info->lock); |
| } |
| |
| void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
| { |
| shmem_undo_range(inode, lstart, lend, false); |
| inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
| } |
| EXPORT_SYMBOL_GPL(shmem_truncate_range); |
| |
| static int shmem_setattr(struct dentry *dentry, struct iattr *attr) |
| { |
| struct inode *inode = dentry->d_inode; |
| int error; |
| |
| error = inode_change_ok(inode, attr); |
| if (error) |
| return error; |
| |
| if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { |
| loff_t oldsize = inode->i_size; |
| loff_t newsize = attr->ia_size; |
| |
| if (newsize != oldsize) { |
| i_size_write(inode, newsize); |
| inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
| } |
| if (newsize < oldsize) { |
| loff_t holebegin = round_up(newsize, PAGE_SIZE); |
| unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
| shmem_truncate_range(inode, newsize, (loff_t)-1); |
| /* unmap again to remove racily COWed private pages */ |
| unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
| } |
| } |
| |
| setattr_copy(inode, attr); |
| if (attr->ia_valid & ATTR_MODE) |
| error = posix_acl_chmod(inode, inode->i_mode); |
| return error; |
| } |
| |
| static void shmem_evict_inode(struct inode *inode) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| |
| if (inode->i_mapping->a_ops == &shmem_aops) { |
| shmem_unacct_size(info->flags, inode->i_size); |
| inode->i_size = 0; |
| shmem_truncate_range(inode, 0, (loff_t)-1); |
| if (!list_empty(&info->swaplist)) { |
| mutex_lock(&shmem_swaplist_mutex); |
| list_del_init(&info->swaplist); |
| mutex_unlock(&shmem_swaplist_mutex); |
| } |
| } else |
| kfree(info->symlink); |
| |
| simple_xattrs_free(&info->xattrs); |
| WARN_ON(inode->i_blocks); |
| shmem_free_inode(inode->i_sb); |
| clear_inode(inode); |
| } |
| |
| /* |
| * If swap found in inode, free it and move page from swapcache to filecache. |
| */ |
| static int shmem_unuse_inode(struct shmem_inode_info *info, |
| swp_entry_t swap, struct page **pagep) |
| { |
| struct address_space *mapping = info->vfs_inode.i_mapping; |
| void *radswap; |
| pgoff_t index; |
| gfp_t gfp; |
| int error = 0; |
| |
| radswap = swp_to_radix_entry(swap); |
| index = radix_tree_locate_item(&mapping->page_tree, radswap); |
| if (index == -1) |
| return 0; |
| |
| /* |
| * Move _head_ to start search for next from here. |
| * But be careful: shmem_evict_inode checks list_empty without taking |
| * mutex, and there's an instant in list_move_tail when info->swaplist |
| * would appear empty, if it were the only one on shmem_swaplist. |
| */ |
| if (shmem_swaplist.next != &info->swaplist) |
| list_move_tail(&shmem_swaplist, &info->swaplist); |
| |
| gfp = mapping_gfp_mask(mapping); |
| if (shmem_should_replace_page(*pagep, gfp)) { |
| mutex_unlock(&shmem_swaplist_mutex); |
| error = shmem_replace_page(pagep, gfp, info, index); |
| mutex_lock(&shmem_swaplist_mutex); |
| /* |
| * We needed to drop mutex to make that restrictive page |
| * allocation, but the inode might have been freed while we |
| * dropped it: although a racing shmem_evict_inode() cannot |
| * complete without emptying the radix_tree, our page lock |
| * on this swapcache page is not enough to prevent that - |
| * free_swap_and_cache() of our swap entry will only |
| * trylock_page(), removing swap from radix_tree whatever. |
| * |
| * We must not proceed to shmem_add_to_page_cache() if the |
| * inode has been freed, but of course we cannot rely on |
| * inode or mapping or info to check that. However, we can |
| * safely check if our swap entry is still in use (and here |
| * it can't have got reused for another page): if it's still |
| * in use, then the inode cannot have been freed yet, and we |
| * can safely proceed (if it's no longer in use, that tells |
| * nothing about the inode, but we don't need to unuse swap). |
| */ |
| if (!page_swapcount(*pagep)) |
| error = -ENOENT; |
| } |
| |
| /* |
| * We rely on shmem_swaplist_mutex, not only to protect the swaplist, |
| * but also to hold up shmem_evict_inode(): so inode cannot be freed |
| * beneath us (pagelock doesn't help until the page is in pagecache). |
| */ |
| if (!error) |
| error = shmem_add_to_page_cache(*pagep, mapping, index, |
| GFP_NOWAIT, radswap); |
| if (error != -ENOMEM) { |
| /* |
| * Truncation and eviction use free_swap_and_cache(), which |
| * only does trylock page: if we raced, best clean up here. |
| */ |
| delete_from_swap_cache(*pagep); |
| set_page_dirty(*pagep); |
| if (!error) { |
| spin_lock(&info->lock); |
| info->swapped--; |
| spin_unlock(&info->lock); |
| swap_free(swap); |
| } |
| error = 1; /* not an error, but entry was found */ |
| } |
| return error; |
| } |
| |
| /* |
| * Search through swapped inodes to find and replace swap by page. |
| */ |
| int shmem_unuse(swp_entry_t swap, struct page *page) |
| { |
| struct list_head *this, *next; |
| struct shmem_inode_info *info; |
| int found = 0; |
| int error = 0; |
| |
| /* |
| * There's a faint possibility that swap page was replaced before |
| * caller locked it: caller will come back later with the right page. |
| */ |
| if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) |
| goto out; |
| |
| /* |
| * Charge page using GFP_KERNEL while we can wait, before taking |
| * the shmem_swaplist_mutex which might hold up shmem_writepage(). |
| * Charged back to the user (not to caller) when swap account is used. |
| */ |
| error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); |
| if (error) |
| goto out; |
| /* No radix_tree_preload: swap entry keeps a place for page in tree */ |
| |
| mutex_lock(&shmem_swaplist_mutex); |
| list_for_each_safe(this, next, &shmem_swaplist) { |
| info = list_entry(this, struct shmem_inode_info, swaplist); |
| if (info->swapped) |
| found = shmem_unuse_inode(info, swap, &page); |
| else |
| list_del_init(&info->swaplist); |
| cond_resched(); |
| if (found) |
| break; |
| } |
| mutex_unlock(&shmem_swaplist_mutex); |
| |
| if (found < 0) |
| error = found; |
| out: |
| unlock_page(page); |
| page_cache_release(page); |
| return error; |
| } |
| |
| /* |
| * Move the page from the page cache to the swap cache. |
| */ |
| static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
| { |
| struct shmem_inode_info *info; |
| struct address_space *mapping; |
| struct inode *inode; |
| swp_entry_t swap; |
| pgoff_t index; |
| |
| BUG_ON(!PageLocked(page)); |
| mapping = page->mapping; |
| index = page->index; |
| inode = mapping->host; |
| info = SHMEM_I(inode); |
| if (info->flags & VM_LOCKED) |
| goto redirty; |
| if (!total_swap_pages) |
| goto redirty; |
| |
| /* |
| * shmem_backing_dev_info's capabilities prevent regular writeback or |
| * sync from ever calling shmem_writepage; but a stacking filesystem |
| * might use ->writepage of its underlying filesystem, in which case |
| * tmpfs should write out to swap only in response to memory pressure, |
| * and not for the writeback threads or sync. |
| */ |
| if (!wbc->for_reclaim) { |
| WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ |
| goto redirty; |
| } |
| |
| /* |
| * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC |
| * value into swapfile.c, the only way we can correctly account for a |
| * fallocated page arriving here is now to initialize it and write it. |
| * |
| * That's okay for a page already fallocated earlier, but if we have |
| * not yet completed the fallocation, then (a) we want to keep track |
| * of this page in case we have to undo it, and (b) it may not be a |
| * good idea to continue anyway, once we're pushing into swap. So |
| * reactivate the page, and let shmem_fallocate() quit when too many. |
| */ |
| if (!PageUptodate(page)) { |
| if (inode->i_private) { |
| struct shmem_falloc *shmem_falloc; |
| spin_lock(&inode->i_lock); |
| shmem_falloc = inode->i_private; |
| if (shmem_falloc && |
| index >= shmem_falloc->start && |
| index < shmem_falloc->next) |
| shmem_falloc->nr_unswapped++; |
| else |
| shmem_falloc = NULL; |
| spin_unlock(&inode->i_lock); |
| if (shmem_falloc) |
| goto redirty; |
| } |
| clear_highpage(page); |
| flush_dcache_page(page); |
| SetPageUptodate(page); |
| } |
| |
| swap = get_swap_page(); |
| if (!swap.val) |
| goto redirty; |
| |
| /* |
| * Add inode to shmem_unuse()'s list of swapped-out inodes, |
| * if it's not already there. Do it now before the page is |
| * moved to swap cache, when its pagelock no longer protects |
| * the inode from eviction. But don't unlock the mutex until |
| * we've incremented swapped, because shmem_unuse_inode() will |
| * prune a !swapped inode from the swaplist under this mutex. |
| */ |
| mutex_lock(&shmem_swaplist_mutex); |
| if (list_empty(&info->swaplist)) |
| list_add_tail(&info->swaplist, &shmem_swaplist); |
| |
| if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { |
| swap_shmem_alloc(swap); |
| shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); |
| |
| spin_lock(&info->lock); |
| info->swapped++; |
| shmem_recalc_inode(inode); |
| spin_unlock(&info->lock); |
| |
| mutex_unlock(&shmem_swaplist_mutex); |
| BUG_ON(page_mapped(page)); |
| swap_writepage(page, wbc); |
| return 0; |
| } |
| |
| mutex_unlock(&shmem_swaplist_mutex); |
| swapcache_free(swap, NULL); |
| redirty: |
| set_page_dirty(page); |
| if (wbc->for_reclaim) |
| return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
| unlock_page(page); |
| return 0; |
| } |
| |
| #ifdef CONFIG_NUMA |
| #ifdef CONFIG_TMPFS |
| static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
| { |
| char buffer[64]; |
| |
| if (!mpol || mpol->mode == MPOL_DEFAULT) |
| return; /* show nothing */ |
| |
| mpol_to_str(buffer, sizeof(buffer), mpol); |
| |
| seq_printf(seq, ",mpol=%s", buffer); |
| } |
| |
| static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
| { |
| struct mempolicy *mpol = NULL; |
| if (sbinfo->mpol) { |
| spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
| mpol = sbinfo->mpol; |
| mpol_get(mpol); |
| spin_unlock(&sbinfo->stat_lock); |
| } |
| return mpol; |
| } |
| #endif /* CONFIG_TMPFS */ |
| |
| static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct vm_area_struct pvma; |
| struct page *page; |
| |
| /* Create a pseudo vma that just contains the policy */ |
| pvma.vm_start = 0; |
| /* Bias interleave by inode number to distribute better across nodes */ |
| pvma.vm_pgoff = index + info->vfs_inode.i_ino; |
| pvma.vm_ops = NULL; |
| pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
| |
| page = swapin_readahead(swap, gfp, &pvma, 0); |
| |
| /* Drop reference taken by mpol_shared_policy_lookup() */ |
| mpol_cond_put(pvma.vm_policy); |
| |
| return page; |
| } |
| |
| static struct page *shmem_alloc_page(gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct vm_area_struct pvma; |
| struct page *page; |
| |
| /* Create a pseudo vma that just contains the policy */ |
| pvma.vm_start = 0; |
| /* Bias interleave by inode number to distribute better across nodes */ |
| pvma.vm_pgoff = index + info->vfs_inode.i_ino; |
| pvma.vm_ops = NULL; |
| pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
| |
| page = alloc_page_vma(gfp, &pvma, 0); |
| |
| /* Drop reference taken by mpol_shared_policy_lookup() */ |
| mpol_cond_put(pvma.vm_policy); |
| |
| return page; |
| } |
| #else /* !CONFIG_NUMA */ |
| #ifdef CONFIG_TMPFS |
| static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
| { |
| } |
| #endif /* CONFIG_TMPFS */ |
| |
| static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| return swapin_readahead(swap, gfp, NULL, 0); |
| } |
| |
| static inline struct page *shmem_alloc_page(gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| return alloc_page(gfp); |
| } |
| #endif /* CONFIG_NUMA */ |
| |
| #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) |
| static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
| { |
| return NULL; |
| } |
| #endif |
| |
| /* |
| * When a page is moved from swapcache to shmem filecache (either by the |
| * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of |
| * shmem_unuse_inode()), it may have been read in earlier from swap, in |
| * ignorance of the mapping it belongs to. If that mapping has special |
| * constraints (like the gma500 GEM driver, which requires RAM below 4GB), |
| * we may need to copy to a suitable page before moving to filecache. |
| * |
| * In a future release, this may well be extended to respect cpuset and |
| * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); |
| * but for now it is a simple matter of zone. |
| */ |
| static bool shmem_should_replace_page(struct page *page, gfp_t gfp) |
| { |
| return page_zonenum(page) > gfp_zone(gfp); |
| } |
| |
| static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct page *oldpage, *newpage; |
| struct address_space *swap_mapping; |
| pgoff_t swap_index; |
| int error; |
| |
| oldpage = *pagep; |
| swap_index = page_private(oldpage); |
| swap_mapping = page_mapping(oldpage); |
| |
| /* |
| * We have arrived here because our zones are constrained, so don't |
| * limit chance of success by further cpuset and node constraints. |
| */ |
| gfp &= ~GFP_CONSTRAINT_MASK; |
| newpage = shmem_alloc_page(gfp, info, index); |
| if (!newpage) |
| return -ENOMEM; |
| |
| page_cache_get(newpage); |
| copy_highpage(newpage, oldpage); |
| flush_dcache_page(newpage); |
| |
| __set_page_locked(newpage); |
| SetPageUptodate(newpage); |
| SetPageSwapBacked(newpage); |
| set_page_private(newpage, swap_index); |
| SetPageSwapCache(newpage); |
| |
| /* |
| * Our caller will very soon move newpage out of swapcache, but it's |
| * a nice clean interface for us to replace oldpage by newpage there. |
| */ |
| spin_lock_irq(&swap_mapping->tree_lock); |
| error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, |
| newpage); |
| if (!error) { |
| __inc_zone_page_state(newpage, NR_FILE_PAGES); |
| __dec_zone_page_state(oldpage, NR_FILE_PAGES); |
| } |
| spin_unlock_irq(&swap_mapping->tree_lock); |
| |
| if (unlikely(error)) { |
| /* |
| * Is this possible? I think not, now that our callers check |
| * both PageSwapCache and page_private after getting page lock; |
| * but be defensive. Reverse old to newpage for clear and free. |
| */ |
| oldpage = newpage; |
| } else { |
| mem_cgroup_replace_page_cache(oldpage, newpage); |
| lru_cache_add_anon(newpage); |
| *pagep = newpage; |
| } |
| |
| ClearPageSwapCache(oldpage); |
| set_page_private(oldpage, 0); |
| |
| unlock_page(oldpage); |
| page_cache_release(oldpage); |
| page_cache_release(oldpage); |
| return error; |
| } |
| |
| /* |
| * shmem_getpage_gfp - find page in cache, or get from swap, or allocate |
| * |
| * If we allocate a new one we do not mark it dirty. That's up to the |
| * vm. If we swap it in we mark it dirty since we also free the swap |
| * entry since a page cannot live in both the swap and page cache |
| */ |
| static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct shmem_inode_info *info; |
| struct shmem_sb_info *sbinfo; |
| struct page *page; |
| swp_entry_t swap; |
| int error; |
| int once = 0; |
| int alloced = 0; |
| |
| if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) |
| return -EFBIG; |
| repeat: |
| swap.val = 0; |
| page = find_lock_page(mapping, index); |
| if (radix_tree_exceptional_entry(page)) { |
| swap = radix_to_swp_entry(page); |
| page = NULL; |
| } |
| |
| if (sgp != SGP_WRITE && sgp != SGP_FALLOC && |
| ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
| error = -EINVAL; |
| goto failed; |
| } |
| |
| /* fallocated page? */ |
| if (page && !PageUptodate(page)) { |
| if (sgp != SGP_READ) |
| goto clear; |
| unlock_page(page); |
| page_cache_release(page); |
| page = NULL; |
| } |
| if (page || (sgp == SGP_READ && !swap.val)) { |
| *pagep = page; |
| return 0; |
| } |
| |
| /* |
| * Fast cache lookup did not find it: |
| * bring it back from swap or allocate. |
| */ |
| info = SHMEM_I(inode); |
| sbinfo = SHMEM_SB(inode->i_sb); |
| |
| if (swap.val) { |
| /* Look it up and read it in.. */ |
| page = lookup_swap_cache(swap); |
| if (!page) { |
| /* here we actually do the io */ |
| if (fault_type) |
| *fault_type |= VM_FAULT_MAJOR; |
| page = shmem_swapin(swap, gfp, info, index); |
| if (!page) { |
| error = -ENOMEM; |
| goto failed; |
| } |
| } |
| |
| /* We have to do this with page locked to prevent races */ |
| lock_page(page); |
| if (!PageSwapCache(page) || page_private(page) != swap.val || |
| !shmem_confirm_swap(mapping, index, swap)) { |
| error = -EEXIST; /* try again */ |
| goto unlock; |
| } |
| if (!PageUptodate(page)) { |
| error = -EIO; |
| goto failed; |
| } |
| wait_on_page_writeback(page); |
| |
| if (shmem_should_replace_page(page, gfp)) { |
| error = shmem_replace_page(&page, gfp, info, index); |
| if (error) |
| goto failed; |
| } |
| |
| error = mem_cgroup_cache_charge(page, current->mm, |
| gfp & GFP_RECLAIM_MASK); |
| if (!error) { |
| error = shmem_add_to_page_cache(page, mapping, index, |
| gfp, swp_to_radix_entry(swap)); |
| /* |
| * We already confirmed swap under page lock, and make |
| * no memory allocation here, so usually no possibility |
| * of error; but free_swap_and_cache() only trylocks a |
| * page, so it is just possible that the entry has been |
| * truncated or holepunched since swap was confirmed. |
| * shmem_undo_range() will have done some of the |
| * unaccounting, now delete_from_swap_cache() will do |
| * the rest (including mem_cgroup_uncharge_swapcache). |
| * Reset swap.val? No, leave it so "failed" goes back to |
| * "repeat": reading a hole and writing should succeed. |
| */ |
| if (error) |
| delete_from_swap_cache(page); |
| } |
| if (error) |
| goto failed; |
| |
| spin_lock(&info->lock); |
| info->swapped--; |
| shmem_recalc_inode(inode); |
| spin_unlock(&info->lock); |
| |
| delete_from_swap_cache(page); |
| set_page_dirty(page); |
| swap_free(swap); |
| |
| } else { |
| if (shmem_acct_block(info->flags)) { |
| error = -ENOSPC; |
| goto failed; |
| } |
| if (sbinfo->max_blocks) { |
| if (percpu_counter_compare(&sbinfo->used_blocks, |
| sbinfo->max_blocks) >= 0) { |
| error = -ENOSPC; |
| goto unacct; |
| } |
| percpu_counter_inc(&sbinfo->used_blocks); |
| } |
| |
| page = shmem_alloc_page(gfp, info, index); |
| if (!page) { |
| error = -ENOMEM; |
| goto decused; |
| } |
| |
| SetPageSwapBacked(page); |
| __set_page_locked(page); |
| error = mem_cgroup_cache_charge(page, current->mm, |
| gfp & GFP_RECLAIM_MASK); |
| if (error) |
| goto decused; |
| error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK); |
| if (!error) { |
| error = shmem_add_to_page_cache(page, mapping, index, |
| gfp, NULL); |
| radix_tree_preload_end(); |
| } |
| if (error) { |
| mem_cgroup_uncharge_cache_page(page); |
| goto decused; |
| } |
| lru_cache_add_anon(page); |
| |
| spin_lock(&info->lock); |
| info->alloced++; |
| inode->i_blocks += BLOCKS_PER_PAGE; |
| shmem_recalc_inode(inode); |
| spin_unlock(&info->lock); |
| alloced = true; |
| |
| /* |
| * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. |
| */ |
| if (sgp == SGP_FALLOC) |
| sgp = SGP_WRITE; |
| clear: |
| /* |
| * Let SGP_WRITE caller clear ends if write does not fill page; |
| * but SGP_FALLOC on a page fallocated earlier must initialize |
| * it now, lest undo on failure cancel our earlier guarantee. |
| */ |
| if (sgp != SGP_WRITE) { |
| clear_highpage(page); |
| flush_dcache_page(page); |
| SetPageUptodate(page); |
| } |
| if (sgp == SGP_DIRTY) |
| set_page_dirty(page); |
| } |
| |
| /* Perhaps the file has been truncated since we checked */ |
| if (sgp != SGP_WRITE && sgp != SGP_FALLOC && |
| ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
| error = -EINVAL; |
| if (alloced) |
| goto trunc; |
| else |
| goto failed; |
| } |
| *pagep = page; |
| return 0; |
| |
| /* |
| * Error recovery. |
| */ |
| trunc: |
| info = SHMEM_I(inode); |
| ClearPageDirty(page); |
| delete_from_page_cache(page); |
| spin_lock(&info->lock); |
| info->alloced--; |
| inode->i_blocks -= BLOCKS_PER_PAGE; |
| spin_unlock(&info->lock); |
| decused: |
| sbinfo = SHMEM_SB(inode->i_sb); |
| if (sbinfo->max_blocks) |
| percpu_counter_add(&sbinfo->used_blocks, -1); |
| unacct: |
| shmem_unacct_blocks(info->flags, 1); |
| failed: |
| if (swap.val && error != -EINVAL && |
| !shmem_confirm_swap(mapping, index, swap)) |
| error = -EEXIST; |
| unlock: |
| if (page) { |
| unlock_page(page); |
| page_cache_release(page); |
| } |
| if (error == -ENOSPC && !once++) { |
| info = SHMEM_I(inode); |
| spin_lock(&info->lock); |
| shmem_recalc_inode(inode); |
| spin_unlock(&info->lock); |
| goto repeat; |
| } |
| if (error == -EEXIST) /* from above or from radix_tree_insert */ |
| goto repeat; |
| return error; |
| } |
| |
| static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
| { |
| struct inode *inode = file_inode(vma->vm_file); |
| int error; |
| int ret = VM_FAULT_LOCKED; |
| |
| error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); |
| if (error) |
| return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); |
| |
| if (ret & VM_FAULT_MAJOR) { |
| count_vm_event(PGMAJFAULT); |
| mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
| } |
| return ret; |
| } |
| |
| #ifdef CONFIG_NUMA |
| static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) |
| { |
| struct inode *inode = file_inode(vma->vm_file); |
| return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); |
| } |
| |
| static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
| unsigned long addr) |
| { |
| struct inode *inode = file_inode(vma->vm_file); |
| pgoff_t index; |
| |
| index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); |
| } |
| #endif |
| |
| int shmem_lock(struct file *file, int lock, struct user_struct *user) |
| { |
| struct inode *inode = file_inode(file); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| int retval = -ENOMEM; |
| |
| spin_lock(&info->lock); |
| if (lock && !(info->flags & VM_LOCKED)) { |
| if (!user_shm_lock(inode->i_size, user)) |
| goto out_nomem; |
| info->flags |= VM_LOCKED; |
| mapping_set_unevictable(file->f_mapping); |
| } |
| if (!lock && (info->flags & VM_LOCKED) && user) { |
| user_shm_unlock(inode->i_size, user); |
| info->flags &= ~VM_LOCKED; |
| mapping_clear_unevictable(file->f_mapping); |
| } |
| retval = 0; |
| |
| out_nomem: |
| spin_unlock(&info->lock); |
| return retval; |
| } |
| |
| static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| file_accessed(file); |
| vma->vm_ops = &shmem_vm_ops; |
| return 0; |
| } |
| |
| static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, |
| umode_t mode, dev_t dev, unsigned long flags) |
| { |
| struct inode *inode; |
| struct shmem_inode_info *info; |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| |
| if (shmem_reserve_inode(sb)) |
| return NULL; |
| |
| inode = new_inode(sb); |
| if (inode) { |
| inode->i_ino = get_next_ino(); |
| inode_init_owner(inode, dir, mode); |
| inode->i_blocks = 0; |
| inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; |
| inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
| inode->i_generation = get_seconds(); |
| info = SHMEM_I(inode); |
| memset(info, 0, (char *)inode - (char *)info); |
| spin_lock_init(&info->lock); |
| info->flags = flags & VM_NORESERVE; |
| INIT_LIST_HEAD(&info->swaplist); |
| simple_xattrs_init(&info->xattrs); |
| cache_no_acl(inode); |
| |
| switch (mode & S_IFMT) { |
| default: |
| inode->i_op = &shmem_special_inode_operations; |
| init_special_inode(inode, mode, dev); |
| break; |
| case S_IFREG: |
| inode->i_mapping->a_ops = &shmem_aops; |
| inode->i_op = &shmem_inode_operations; |
| inode->i_fop = &shmem_file_operations; |
| mpol_shared_policy_init(&info->policy, |
| shmem_get_sbmpol(sbinfo)); |
| break; |
| case S_IFDIR: |
| inc_nlink(inode); |
| /* Some things misbehave if size == 0 on a directory */ |
| inode->i_size = 2 * BOGO_DIRENT_SIZE; |
| inode->i_op = &shmem_dir_inode_operations; |
| inode->i_fop = &simple_dir_operations; |
| break; |
| case S_IFLNK: |
| /* |
| * Must not load anything in the rbtree, |
| * mpol_free_shared_policy will not be called. |
| */ |
| mpol_shared_policy_init(&info->policy, NULL); |
| break; |
| } |
| } else |
| shmem_free_inode(sb); |
| return inode; |
| } |
| |
| #ifdef CONFIG_TMPFS |
| static const struct inode_operations shmem_symlink_inode_operations; |
| static const struct inode_operations shmem_short_symlink_operations; |
| |
| #ifdef CONFIG_TMPFS_XATTR |
| static int shmem_initxattrs(struct inode *, const struct xattr *, void *); |
| #else |
| #define shmem_initxattrs NULL |
| #endif |
| |
| static int |
| shmem_write_begin(struct file *file, struct address_space *mapping, |
| loff_t pos, unsigned len, unsigned flags, |
| struct page **pagep, void **fsdata) |
| { |
| struct inode *inode = mapping->host; |
| pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
| return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); |
| } |
| |
| static int |
| shmem_write_end(struct file *file, struct address_space *mapping, |
| loff_t pos, unsigned len, unsigned copied, |
| struct page *page, void *fsdata) |
| { |
| struct inode *inode = mapping->host; |
| |
| if (pos + copied > inode->i_size) |
| i_size_write(inode, pos + copied); |
| |
| if (!PageUptodate(page)) { |
| if (copied < PAGE_CACHE_SIZE) { |
| unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
| zero_user_segments(page, 0, from, |
| from + copied, PAGE_CACHE_SIZE); |
| } |
| SetPageUptodate(page); |
| } |
| set_page_dirty(page); |
| unlock_page(page); |
| page_cache_release(page); |
| |
| return copied; |
| } |
| |
| static ssize_t shmem_file_aio_read(struct kiocb *iocb, |
| const struct iovec *iov, unsigned long nr_segs, loff_t pos) |
| { |
| struct file *file = iocb->ki_filp; |
| struct inode *inode = file_inode(file); |
| struct address_space *mapping = inode->i_mapping; |
| pgoff_t index; |
| unsigned long offset; |
| enum sgp_type sgp = SGP_READ; |
| int error; |
| ssize_t retval; |
| size_t count; |
| loff_t *ppos = &iocb->ki_pos; |
| struct iov_iter iter; |
| |
| retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
| if (retval) |
| return retval; |
| iov_iter_init(&iter, iov, nr_segs, count, 0); |
| |
| /* |
| * Might this read be for a stacking filesystem? Then when reading |
| * holes of a sparse file, we actually need to allocate those pages, |
| * and even mark them dirty, so it cannot exceed the max_blocks limit. |
| */ |
| if (segment_eq(get_fs(), KERNEL_DS)) |
| sgp = SGP_DIRTY; |
| |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| offset = *ppos & ~PAGE_CACHE_MASK; |
| |
| for (;;) { |
| struct page *page = NULL; |
| pgoff_t end_index; |
| unsigned long nr, ret; |
| loff_t i_size = i_size_read(inode); |
| |
| end_index = i_size >> PAGE_CACHE_SHIFT; |
| if (index > end_index) |
| break; |
| if (index == end_index) { |
| nr = i_size & ~PAGE_CACHE_MASK; |
| if (nr <= offset) |
| break; |
| } |
| |
| error = shmem_getpage(inode, index, &page, sgp, NULL); |
| if (error) { |
| if (error == -EINVAL) |
| error = 0; |
| break; |
| } |
| if (page) |
| unlock_page(page); |
| |
| /* |
| * We must evaluate after, since reads (unlike writes) |
| * are called without i_mutex protection against truncate |
| */ |
| nr = PAGE_CACHE_SIZE; |
| i_size = i_size_read(inode); |
| end_index = i_size >> PAGE_CACHE_SHIFT; |
| if (index == end_index) { |
| nr = i_size & ~PAGE_CACHE_MASK; |
| if (nr <= offset) { |
| if (page) |
| page_cache_release(page); |
| break; |
| } |
| } |
| nr -= offset; |
| |
| if (page) { |
| /* |
| * If users can be writing to this page using arbitrary |
| * virtual addresses, take care about potential aliasing |
| * before reading the page on the kernel side. |
| */ |
| if (mapping_writably_mapped(mapping)) |
| flush_dcache_page(page); |
| /* |
| * Mark the page accessed if we read the beginning. |
| */ |
| if (!offset) |
| mark_page_accessed(page); |
| } else { |
| page = ZERO_PAGE(0); |
| page_cache_get(page); |
| } |
| |
| /* |
| * Ok, we have the page, and it's up-to-date, so |
| * now we can copy it to user space... |
| */ |
| ret = copy_page_to_iter(page, offset, nr, &iter); |
| retval += ret; |
| offset += ret; |
| index += offset >> PAGE_CACHE_SHIFT; |
| offset &= ~PAGE_CACHE_MASK; |
| |
| page_cache_release(page); |
| if (!iov_iter_count(&iter)) |
| break; |
| if (ret < nr) { |
| error = -EFAULT; |
| break; |
| } |
| cond_resched(); |
| } |
| |
| *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
| file_accessed(file); |
| return retval ? retval : error; |
| } |
| |
| static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, |
| struct pipe_inode_info *pipe, size_t len, |
| unsigned int flags) |
| { |
| struct address_space *mapping = in->f_mapping; |
| struct inode *inode = mapping->host; |
| unsigned int loff, nr_pages, req_pages; |
| struct page *pages[PIPE_DEF_BUFFERS]; |
| struct partial_page partial[PIPE_DEF_BUFFERS]; |
| struct page *page; |
| pgoff_t index, end_index; |
| loff_t isize, left; |
| int error, page_nr; |
| struct splice_pipe_desc spd = { |
| .pages = pages, |
| .partial = partial, |
| .nr_pages_max = PIPE_DEF_BUFFERS, |
| .flags = flags, |
| .ops = &page_cache_pipe_buf_ops, |
| .spd_release = spd_release_page, |
| }; |
| |
| isize = i_size_read(inode); |
| if (unlikely(*ppos >= isize)) |
| return 0; |
| |
| left = isize - *ppos; |
| if (unlikely(left < len)) |
| len = left; |
| |
| if (splice_grow_spd(pipe, &spd)) |
| return -ENOMEM; |
| |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| loff = *ppos & ~PAGE_CACHE_MASK; |
| req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| nr_pages = min(req_pages, pipe->buffers); |
| |
| spd.nr_pages = find_get_pages_contig(mapping, index, |
| nr_pages, spd.pages); |
| index += spd.nr_pages; |
| error = 0; |
| |
| while (spd.nr_pages < nr_pages) { |
| error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); |
| if (error) |
| break; |
| unlock_page(page); |
| spd.pages[spd.nr_pages++] = page; |
| index++; |
| } |
| |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| nr_pages = spd.nr_pages; |
| spd.nr_pages = 0; |
| |
| for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
| unsigned int this_len; |
| |
| if (!len) |
| break; |
| |
| this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
| page = spd.pages[page_nr]; |
| |
| if (!PageUptodate(page) || page->mapping != mapping) { |
| error = shmem_getpage(inode, index, &page, |
| SGP_CACHE, NULL); |
| if (error) |
| break; |
| unlock_page(page); |
| page_cache_release(spd.pages[page_nr]); |
| spd.pages[page_nr] = page; |
| } |
| |
| isize = i_size_read(inode); |
| end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
| if (unlikely(!isize || index > end_index)) |
| break; |
| |
| if (end_index == index) { |
| unsigned int plen; |
| |
| plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
| if (plen <= loff) |
| break; |
| |
| this_len = min(this_len, plen - loff); |
| len = this_len; |
| } |
| |
| spd.partial[page_nr].offset = loff; |
| spd.partial[page_nr].len = this_len; |
| len -= this_len; |
| loff = 0; |
| spd.nr_pages++; |
| index++; |
| } |
| |
| while (page_nr < nr_pages) |
| page_cache_release(spd.pages[page_nr++]); |
| |
| if (spd.nr_pages) |
| error = splice_to_pipe(pipe, &spd); |
| |
| splice_shrink_spd(&spd); |
| |
| if (error > 0) { |
| *ppos += error; |
| file_accessed(in); |
| } |
| return error; |
| } |
| |
| /* |
| * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. |
| */ |
| static pgoff_t shmem_seek_hole_data(struct address_space *mapping, |
| pgoff_t index, pgoff_t end, int whence) |
| { |
| struct page *page; |
| struct pagevec pvec; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| bool done = false; |
| int i; |
| |
| pagevec_init(&pvec, 0); |
| pvec.nr = 1; /* start small: we may be there already */ |
| while (!done) { |
| pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
| pvec.nr, pvec.pages, indices); |
| if (!pvec.nr) { |
| if (whence == SEEK_DATA) |
| index = end; |
| break; |
| } |
| for (i = 0; i < pvec.nr; i++, index++) { |
| if (index < indices[i]) { |
| if (whence == SEEK_HOLE) { |
| done = true; |
| break; |
| } |
| index = indices[i]; |
| } |
| page = pvec.pages[i]; |
| if (page && !radix_tree_exceptional_entry(page)) { |
| if (!PageUptodate(page)) |
| page = NULL; |
| } |
| if (index >= end || |
| (page && whence == SEEK_DATA) || |
| (!page && whence == SEEK_HOLE)) { |
| done = true; |
| break; |
| } |
| } |
| shmem_deswap_pagevec(&pvec); |
| pagevec_release(&pvec); |
| pvec.nr = PAGEVEC_SIZE; |
| cond_resched(); |
| } |
| return index; |
| } |
| |
| static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| pgoff_t start, end; |
| loff_t new_offset; |
| |
| if (whence != SEEK_DATA && whence != SEEK_HOLE) |
| return generic_file_llseek_size(file, offset, whence, |
| MAX_LFS_FILESIZE, i_size_read(inode)); |
| mutex_lock(&inode->i_mutex); |
| /* We're holding i_mutex so we can access i_size directly */ |
| |
| if (offset < 0) |
| offset = -EINVAL; |
| else if (offset >= inode->i_size) |
| offset = -ENXIO; |
| else { |
| start = offset >> PAGE_CACHE_SHIFT; |
| end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| new_offset = shmem_seek_hole_data(mapping, start, end, whence); |
| new_offset <<= PAGE_CACHE_SHIFT; |
| if (new_offset > offset) { |
| if (new_offset < inode->i_size) |
| offset = new_offset; |
| else if (whence == SEEK_DATA) |
| offset = -ENXIO; |
| else |
| offset = inode->i_size; |
| } |
| } |
| |
| if (offset >= 0) |
| offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE); |
| mutex_unlock(&inode->i_mutex); |
| return offset; |
| } |
| |
| static long shmem_fallocate(struct file *file, int mode, loff_t offset, |
| loff_t len) |
| { |
| struct inode *inode = file_inode(file); |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| struct shmem_falloc shmem_falloc; |
| pgoff_t start, index, end; |
| int error; |
| |
| mutex_lock(&inode->i_mutex); |
| |
| if (mode & FALLOC_FL_PUNCH_HOLE) { |
| struct address_space *mapping = file->f_mapping; |
| loff_t unmap_start = round_up(offset, PAGE_SIZE); |
| loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; |
| |
| if ((u64)unmap_end > (u64)unmap_start) |
| unmap_mapping_range(mapping, unmap_start, |
| 1 + unmap_end - unmap_start, 0); |
| shmem_truncate_range(inode, offset, offset + len - 1); |
| /* No need to unmap again: hole-punching leaves COWed pages */ |
| error = 0; |
| goto out; |
| } |
| |
| /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ |
| error = inode_newsize_ok(inode, offset + len); |
| if (error) |
| goto out; |
| |
| start = offset >> PAGE_CACHE_SHIFT; |
| end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| /* Try to avoid a swapstorm if len is impossible to satisfy */ |
| if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { |
| error = -ENOSPC; |
| goto out; |
| } |
| |
| shmem_falloc.start = start; |
| shmem_falloc.next = start; |
| shmem_falloc.nr_falloced = 0; |
| shmem_falloc.nr_unswapped = 0; |
| spin_lock(&inode->i_lock); |
| inode->i_private = &shmem_falloc; |
| spin_unlock(&inode->i_lock); |
| |
| for (index = start; index < end; index++) { |
| struct page *page; |
| |
| /* |
| * Good, the fallocate(2) manpage permits EINTR: we may have |
| * been interrupted because we are using up too much memory. |
| */ |
| if (signal_pending(current)) |
| error = -EINTR; |
| else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) |
| error = -ENOMEM; |
| else |
| error = shmem_getpage(inode, index, &page, SGP_FALLOC, |
| NULL); |
| if (error) { |
| /* Remove the !PageUptodate pages we added */ |
| shmem_undo_range(inode, |
| (loff_t)start << PAGE_CACHE_SHIFT, |
| (loff_t)index << PAGE_CACHE_SHIFT, true); |
| goto undone; |
| } |
| |
| /* |
| * Inform shmem_writepage() how far we have reached. |
| * No need for lock or barrier: we have the page lock. |
| */ |
| shmem_falloc.next++; |
| if (!PageUptodate(page)) |
| shmem_falloc.nr_falloced++; |
| |
| /* |
| * If !PageUptodate, leave it that way so that freeable pages |
| * can be recognized if we need to rollback on error later. |
| * But set_page_dirty so that memory pressure will swap rather |
| * than free the pages we are allocating (and SGP_CACHE pages |
| * might still be clean: we now need to mark those dirty too). |
| */ |
| set_page_dirty(page); |
| unlock_page(page); |
| page_cache_release(page); |
| cond_resched(); |
| } |
| |
| if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) |
| i_size_write(inode, offset + len); |
| inode->i_ctime = CURRENT_TIME; |
| undone: |
| spin_lock(&inode->i_lock); |
| inode->i_private = NULL; |
| spin_unlock(&inode->i_lock); |
| out: |
| mutex_unlock(&inode->i_mutex); |
| return error; |
| } |
| |
| static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
| |
| buf->f_type = TMPFS_MAGIC; |
| buf->f_bsize = PAGE_CACHE_SIZE; |
| buf->f_namelen = NAME_MAX; |
| if (sbinfo->max_blocks) { |
| buf->f_blocks = sbinfo->max_blocks; |
| buf->f_bavail = |
| buf->f_bfree = sbinfo->max_blocks - |
| percpu_counter_sum(&sbinfo->used_blocks); |
| } |
| if (sbinfo->max_inodes) { |
| buf->f_files = sbinfo->max_inodes; |
| buf->f_ffree = sbinfo->free_inodes; |
| } |
| /* else leave those fields 0 like simple_statfs */ |
| return 0; |
| } |
| |
| /* |
| * File creation. Allocate an inode, and we're done.. |
| */ |
| static int |
| shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
| { |
| struct inode *inode; |
| int error = -ENOSPC; |
| |
| inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); |
| if (inode) { |
| error = simple_acl_create(dir, inode); |
| if (error) |
| goto out_iput; |
| error = security_inode_init_security(inode, dir, |
| &dentry->d_name, |
| shmem_initxattrs, NULL); |
| if (error && error != -EOPNOTSUPP) |
| goto out_iput; |
| |
| error = 0; |
| dir->i_size += BOGO_DIRENT_SIZE; |
| dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| d_instantiate(dentry, inode); |
| dget(dentry); /* Extra count - pin the dentry in core */ |
| } |
| return error; |
| out_iput: |
| iput(inode); |
| return error; |
| } |
| |
| static int |
| shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) |
| { |
| struct inode *inode; |
| int error = -ENOSPC; |
| |
| inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE); |
| if (inode) { |
| error = security_inode_init_security(inode, dir, |
| NULL, |
| shmem_initxattrs, NULL); |
| if (error && error != -EOPNOTSUPP) |
| goto out_iput; |
| error = simple_acl_create(dir, inode); |
| if (error) |
| goto out_iput; |
| d_tmpfile(dentry, inode); |
| } |
| return error; |
| out_iput: |
| iput(inode); |
| return error; |
| } |
| |
| static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
| { |
| int error; |
| |
| if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
| return error; |
| inc_nlink(dir); |
| return 0; |
| } |
| |
| static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
| bool excl) |
| { |
| return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
| } |
| |
| /* |
| * Link a file.. |
| */ |
| static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
| { |
| struct inode *inode = old_dentry->d_inode; |
| int ret; |
| |
| /* |
| * No ordinary (disk based) filesystem counts links as inodes; |
| * but each new link needs a new dentry, pinning lowmem, and |
| * tmpfs dentries cannot be pruned until they are unlinked. |
| */ |
| ret = shmem_reserve_inode(inode->i_sb); |
| if (ret) |
| goto out; |
| |
| dir->i_size += BOGO_DIRENT_SIZE; |
| inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| inc_nlink(inode); |
| ihold(inode); /* New dentry reference */ |
| dget(dentry); /* Extra pinning count for the created dentry */ |
| d_instantiate(dentry, inode); |
| out: |
| return ret; |
| } |
| |
| static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
| { |
| struct inode *inode = dentry->d_inode; |
| |
| if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
| shmem_free_inode(inode->i_sb); |
| |
| dir->i_size -= BOGO_DIRENT_SIZE; |
| inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| drop_nlink(inode); |
| dput(dentry); /* Undo the count from "create" - this does all the work */ |
| return 0; |
| } |
| |
| static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
| { |
| if (!simple_empty(dentry)) |
| return -ENOTEMPTY; |
| |
| drop_nlink(dentry->d_inode); |
| drop_nlink(dir); |
| return shmem_unlink(dir, dentry); |
| } |
| |
| /* |
| * The VFS layer already does all the dentry stuff for rename, |
| * we just have to decrement the usage count for the target if |
| * it exists so that the VFS layer correctly free's it when it |
| * gets overwritten. |
| */ |
| static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
| { |
| struct inode *inode = old_dentry->d_inode; |
| int they_are_dirs = S_ISDIR(inode->i_mode); |
| |
| if (!simple_empty(new_dentry)) |
| return -ENOTEMPTY; |
| |
| if (new_dentry->d_inode) { |
| (void) shmem_unlink(new_dir, new_dentry); |
| if (they_are_dirs) |
| drop_nlink(old_dir); |
| } else if (they_are_dirs) { |
| drop_nlink(old_dir); |
| inc_nlink(new_dir); |
| } |
| |
| old_dir->i_size -= BOGO_DIRENT_SIZE; |
| new_dir->i_size += BOGO_DIRENT_SIZE; |
| old_dir->i_ctime = old_dir->i_mtime = |
| new_dir->i_ctime = new_dir->i_mtime = |
| inode->i_ctime = CURRENT_TIME; |
| return 0; |
| } |
| |
| static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
| { |
| int error; |
| int len; |
| struct inode *inode; |
| struct page *page; |
| char *kaddr; |
| struct shmem_inode_info *info; |
| |
| len = strlen(symname) + 1; |
| if (len > PAGE_CACHE_SIZE) |
| return -ENAMETOOLONG; |
| |
| inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); |
| if (!inode) |
| return -ENOSPC; |
| |
| error = security_inode_init_security(inode, dir, &dentry->d_name, |
| shmem_initxattrs, NULL); |
| if (error) { |
| if (error != -EOPNOTSUPP) { |
| iput(inode); |
| return error; |
| } |
| error = 0; |
| } |
| |
| info = SHMEM_I(inode); |
| inode->i_size = len-1; |
| if (len <= SHORT_SYMLINK_LEN) { |
| info->symlink = kmemdup(symname, len, GFP_KERNEL); |
| if (!info->symlink) { |
| iput(inode); |
| return -ENOMEM; |
| } |
| inode->i_op = &shmem_short_symlink_operations; |
| } else { |
| error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); |
| if (error) { |
| iput(inode); |
| return error; |
| } |
| inode->i_mapping->a_ops = &shmem_aops; |
| inode->i_op = &shmem_symlink_inode_operations; |
| kaddr = kmap_atomic(page); |
| memcpy(kaddr, symname, len); |
| kunmap_atomic(kaddr); |
| SetPageUptodate(page); |
| set_page_dirty(page); |
| unlock_page(page); |
| page_cache_release(page); |
| } |
| dir->i_size += BOGO_DIRENT_SIZE; |
| dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
| d_instantiate(dentry, inode); |
| dget(dentry); |
| return 0; |
| } |
| |
| static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) |
| { |
| nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); |
| return NULL; |
| } |
| |
| static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
| { |
| struct page *page = NULL; |
| int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); |
| nd_set_link(nd, error ? ERR_PTR(error) : kmap(page)); |
| if (page) |
| unlock_page(page); |
| return page; |
| } |
| |
| static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
| { |
| if (!IS_ERR(nd_get_link(nd))) { |
| struct page *page = cookie; |
| kunmap(page); |
| mark_page_accessed(page); |
| page_cache_release(page); |
| } |
| } |
| |
| #ifdef CONFIG_TMPFS_XATTR |
| /* |
| * Superblocks without xattr inode operations may get some security.* xattr |
| * support from the LSM "for free". As soon as we have any other xattrs |
| * like ACLs, we also need to implement the security.* handlers at |
| * filesystem level, though. |
| */ |
| |
| /* |
| * Callback for security_inode_init_security() for acquiring xattrs. |
| */ |
| static int shmem_initxattrs(struct inode *inode, |
| const struct xattr *xattr_array, |
| void *fs_info) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| const struct xattr *xattr; |
| struct simple_xattr *new_xattr; |
| size_t len; |
| |
| for (xattr = xattr_array; xattr->name != NULL; xattr++) { |
| new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); |
| if (!new_xattr) |
| return -ENOMEM; |
| |
| len = strlen(xattr->name) + 1; |
| new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, |
| GFP_KERNEL); |
| if (!new_xattr->name) { |
| kfree(new_xattr); |
| return -ENOMEM; |
| } |
| |
| memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, |
| XATTR_SECURITY_PREFIX_LEN); |
| memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, |
| xattr->name, len); |
| |
| simple_xattr_list_add(&info->xattrs, new_xattr); |
| } |
| |
| return 0; |
| } |
| |
| static const struct xattr_handler *shmem_xattr_handlers[] = { |
| #ifdef CONFIG_TMPFS_POSIX_ACL |
| &posix_acl_access_xattr_handler, |
| &posix_acl_default_xattr_handler, |
| #endif |
| NULL |
| }; |
| |
| static int shmem_xattr_validate(const char *name) |
| { |
| struct { const char *prefix; size_t len; } arr[] = { |
| { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, |
| { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } |
| }; |
| int i; |
| |
| for (i = 0; i < ARRAY_SIZE(arr); i++) { |
| size_t preflen = arr[i].len; |
| if (strncmp(name, arr[i].prefix, preflen) == 0) { |
| if (!name[preflen]) |
| return -EINVAL; |
| return 0; |
| } |
| } |
| return -EOPNOTSUPP; |
| } |
| |
| static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, |
| void *buffer, size_t size) |
| { |
| struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
| int err; |
| |
| /* |
| * If this is a request for a synthetic attribute in the system.* |
| * namespace use the generic infrastructure to resolve a handler |
| * for it via sb->s_xattr. |
| */ |
| if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
| return generic_getxattr(dentry, name, buffer, size); |
| |
| err = shmem_xattr_validate(name); |
| if (err) |
| return err; |
| |
| return simple_xattr_get(&info->xattrs, name, buffer, size); |
| } |
| |
| static int shmem_setxattr(struct dentry *dentry, const char *name, |
| const void *value, size_t size, int flags) |
| { |
| struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
| int err; |
| |
| /* |
| * If this is a request for a synthetic attribute in the system.* |
| * namespace use the generic infrastructure to resolve a handler |
| * for it via sb->s_xattr. |
| */ |
| if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
| return generic_setxattr(dentry, name, value, size, flags); |
| |
| err = shmem_xattr_validate(name); |
| if (err) |
| return err; |
| |
| return simple_xattr_set(&info->xattrs, name, value, size, flags); |
| } |
| |
| static int shmem_removexattr(struct dentry *dentry, const char *name) |
| { |
| struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
| int err; |
| |
| /* |
| * If this is a request for a synthetic attribute in the system.* |
| * namespace use the generic infrastructure to resolve a handler |
| * for it via sb->s_xattr. |
| */ |
| if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
| return generic_removexattr(dentry, name); |
| |
| err = shmem_xattr_validate(name); |
| if (err) |
| return err; |
| |
| return simple_xattr_remove(&info->xattrs, name); |
| } |
| |
| static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) |
| { |
| struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
| return simple_xattr_list(&info->xattrs, buffer, size); |
| } |
| #endif /* CONFIG_TMPFS_XATTR */ |
| |
| static const struct inode_operations shmem_short_symlink_operations = { |
| .readlink = generic_readlink, |
| .follow_link = shmem_follow_short_symlink, |
| #ifdef CONFIG_TMPFS_XATTR |
| .setxattr = shmem_setxattr, |
| .getxattr = shmem_getxattr, |
| .listxattr = shmem_listxattr, |
| .removexattr = shmem_removexattr, |
| #endif |
| }; |
| |
| static const struct inode_operations shmem_symlink_inode_operations = { |
| .readlink = generic_readlink, |
| .follow_link = shmem_follow_link, |
| .put_link = shmem_put_link, |
| #ifdef CONFIG_TMPFS_XATTR |
| .setxattr = shmem_setxattr, |
| .getxattr = shmem_getxattr, |
| .listxattr = shmem_listxattr, |
| .removexattr = shmem_removexattr, |
| #endif |
| }; |
| |
| static struct dentry *shmem_get_parent(struct dentry *child) |
| { |
| return ERR_PTR(-ESTALE); |
| } |
| |
| static int shmem_match(struct inode *ino, void *vfh) |
| { |
| __u32 *fh = vfh; |
| __u64 inum = fh[2]; |
| inum = (inum << 32) | fh[1]; |
| return ino->i_ino == inum && fh[0] == ino->i_generation; |
| } |
| |
| static struct dentry *shmem_fh_to_dentry(struct super_block *sb, |
| struct fid *fid, int fh_len, int fh_type) |
| { |
| struct inode *inode; |
| struct dentry *dentry = NULL; |
| u64 inum; |
| |
| if (fh_len < 3) |
| return NULL; |
| |
| inum = fid->raw[2]; |
| inum = (inum << 32) | fid->raw[1]; |
| |
| inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), |
| shmem_match, fid->raw); |
| if (inode) { |
| dentry = d_find_alias(inode); |
| iput(inode); |
| } |
| |
| return dentry; |
| } |
| |
| static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, |
| struct inode *parent) |
| { |
| if (*len < 3) { |
| *len = 3; |
| return FILEID_INVALID; |
| } |
| |
| if (inode_unhashed(inode)) { |
| /* Unfortunately insert_inode_hash is not idempotent, |
| * so as we hash inodes here rather than at creation |
| * time, we need a lock to ensure we only try |
| * to do it once |
| */ |
| static DEFINE_SPINLOCK(lock); |
| spin_lock(&lock); |
| if (inode_unhashed(inode)) |
| __insert_inode_hash(inode, |
| inode->i_ino + inode->i_generation); |
| spin_unlock(&lock); |
| } |
| |
| fh[0] = inode->i_generation; |
| fh[1] = inode->i_ino; |
| fh[2] = ((__u64)inode->i_ino) >> 32; |
| |
| *len = 3; |
| return 1; |
| } |
| |
| static const struct export_operations shmem_export_ops = { |
| .get_parent = shmem_get_parent, |
| .encode_fh = shmem_encode_fh, |
| .fh_to_dentry = shmem_fh_to_dentry, |
| }; |
| |
| static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, |
| bool remount) |
| { |
| char *this_char, *value, *rest; |
| struct mempolicy *mpol = NULL; |
| uid_t uid; |
| gid_t gid; |
| |
| while (options != NULL) { |
| this_char = options; |
| for (;;) { |
| /* |
| * NUL-terminate this option: unfortunately, |
| * mount options form a comma-separated list, |
| * but mpol's nodelist may also contain commas. |
| */ |
| options = strchr(options, ','); |
| if (options == NULL) |
| break; |
| options++; |
| if (!isdigit(*options)) { |
| options[-1] = '\0'; |
| break; |
| } |
| } |
| if (!*this_char) |
| continue; |
| if ((value = strchr(this_char,'=')) != NULL) { |
| *value++ = 0; |
| } else { |
| printk(KERN_ERR |
| "tmpfs: No value for mount option '%s'\n", |
| this_char); |
| goto error; |
| } |
| |
| if (!strcmp(this_char,"size")) { |
| unsigned long long size; |
| size = memparse(value,&rest); |
| if (*rest == '%') { |
| size <<= PAGE_SHIFT; |
| size *= totalram_pages; |
| do_div(size, 100); |
| rest++; |
| } |
| if (*rest) |
| goto bad_val; |
| sbinfo->max_blocks = |
| DIV_ROUND_UP(size, PAGE_CACHE_SIZE); |
| } else if (!strcmp(this_char,"nr_blocks")) { |
| sbinfo->max_blocks = memparse(value, &rest); |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"nr_inodes")) { |
| sbinfo->max_inodes = memparse(value, &rest); |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"mode")) { |
| if (remount) |
| continue; |
| sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; |
| if (*rest) |
| goto bad_val; |
| } else if (!strcmp(this_char,"uid")) { |
| if (remount) |
| continue; |
| uid = simple_strtoul(value, &rest, 0); |
| if (*rest) |
| goto bad_val; |
| sbinfo->uid = make_kuid(current_user_ns(), uid); |
| if (!uid_valid(sbinfo->uid)) |
| goto bad_val; |
| } else if (!strcmp(this_char,"gid")) { |
| if (remount) |
| continue; |
| gid = simple_strtoul(value, &rest, 0); |
| if (*rest) |
| goto bad_val; |
| sbinfo->gid = make_kgid(current_user_ns(), gid); |
| if (!gid_valid(sbinfo->gid)) |
| goto bad_val; |
| } else if (!strcmp(this_char,"mpol")) { |
| mpol_put(mpol); |
| mpol = NULL; |
| if (mpol_parse_str(value, &mpol)) |
| goto bad_val; |
| } else { |
| printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
| this_char); |
| goto error; |
| } |
| } |
| sbinfo->mpol = mpol; |
| return 0; |
| |
| bad_val: |
| printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
| value, this_char); |
| error: |
| mpol_put(mpol); |
| return 1; |
| |
| } |
| |
| static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| struct shmem_sb_info config = *sbinfo; |
| unsigned long inodes; |
| int error = -EINVAL; |
| |
| config.mpol = NULL; |
| if (shmem_parse_options(data, &config, true)) |
| return error; |
| |
| spin_lock(&sbinfo->stat_lock); |
| inodes = sbinfo->max_inodes - sbinfo->free_inodes; |
| if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) |
| goto out; |
| if (config.max_inodes < inodes) |
| goto out; |
| /* |
| * Those tests disallow limited->unlimited while any are in use; |
| * but we must separately disallow unlimited->limited, because |
| * in that case we have no record of how much is already in use. |
| */ |
| if (config.max_blocks && !sbinfo->max_blocks) |
| goto out; |
| if (config.max_inodes && !sbinfo->max_inodes) |
| goto out; |
| |
| error = 0; |
| sbinfo->max_blocks = config.max_blocks; |
| sbinfo->max_inodes = config.max_inodes; |
| sbinfo->free_inodes = config.max_inodes - inodes; |
| |
| /* |
| * Preserve previous mempolicy unless mpol remount option was specified. |
| */ |
| if (config.mpol) { |
| mpol_put(sbinfo->mpol); |
| sbinfo->mpol = config.mpol; /* transfers initial ref */ |
| } |
| out: |
| spin_unlock(&sbinfo->stat_lock); |
| return error; |
| } |
| |
| static int shmem_show_options(struct seq_file *seq, struct dentry *root) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); |
| |
| if (sbinfo->max_blocks != shmem_default_max_blocks()) |
| seq_printf(seq, ",size=%luk", |
| sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); |
| if (sbinfo->max_inodes != shmem_default_max_inodes()) |
| seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); |
| if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) |
| seq_printf(seq, ",mode=%03ho", sbinfo->mode); |
| if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) |
| seq_printf(seq, ",uid=%u", |
| from_kuid_munged(&init_user_ns, sbinfo->uid)); |
| if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) |
| seq_printf(seq, ",gid=%u", |
| from_kgid_munged(&init_user_ns, sbinfo->gid)); |
| shmem_show_mpol(seq, sbinfo->mpol); |
| return 0; |
| } |
| #endif /* CONFIG_TMPFS */ |
| |
| static void shmem_put_super(struct super_block *sb) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| |
| percpu_counter_destroy(&sbinfo->used_blocks); |
| mpol_put(sbinfo->mpol); |
| kfree(sbinfo); |
| sb->s_fs_info = NULL; |
| } |
| |
| int shmem_fill_super(struct super_block *sb, void *data, int silent) |
| { |
| struct inode *inode; |
| struct shmem_sb_info *sbinfo; |
| int err = -ENOMEM; |
| |
| /* Round up to L1_CACHE_BYTES to resist false sharing */ |
| sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), |
| L1_CACHE_BYTES), GFP_KERNEL); |
| if (!sbinfo) |
| return -ENOMEM; |
| |
| sbinfo->mode = S_IRWXUGO | S_ISVTX; |
| sbinfo->uid = current_fsuid(); |
| sbinfo->gid = current_fsgid(); |
| sb->s_fs_info = sbinfo; |
| |
| #ifdef CONFIG_TMPFS |
| /* |
| * Per default we only allow half of the physical ram per |
| * tmpfs instance, limiting inodes to one per page of lowmem; |
| * but the internal instance is left unlimited. |
| */ |
| if (!(sb->s_flags & MS_KERNMOUNT)) { |
| sbinfo->max_blocks = shmem_default_max_blocks(); |
| sbinfo->max_inodes = shmem_default_max_inodes(); |
| if (shmem_parse_options(data, sbinfo, false)) { |
| err = -EINVAL; |
| goto failed; |
| } |
| } else { |
| sb->s_flags |= MS_NOUSER; |
| } |
| sb->s_export_op = &shmem_export_ops; |
| sb->s_flags |= MS_NOSEC; |
| #else |
| sb->s_flags |= MS_NOUSER; |
| #endif |
| |
| spin_lock_init(&sbinfo->stat_lock); |
| if (percpu_counter_init(&sbinfo->used_blocks, 0)) |
| goto failed; |
| sbinfo->free_inodes = sbinfo->max_inodes; |
| |
| sb->s_maxbytes = MAX_LFS_FILESIZE; |
| sb->s_blocksize = PAGE_CACHE_SIZE; |
| sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
| sb->s_magic = TMPFS_MAGIC; |
| sb->s_op = &shmem_ops; |
| sb->s_time_gran = 1; |
| #ifdef CONFIG_TMPFS_XATTR |
| sb->s_xattr = shmem_xattr_handlers; |
| #endif |
| #ifdef CONFIG_TMPFS_POSIX_ACL |
| sb->s_flags |= MS_POSIXACL; |
| #endif |
| |
| inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); |
| if (!inode) |
| goto failed; |
| inode->i_uid = sbinfo->uid; |
| inode->i_gid = sbinfo->gid; |
| sb->s_root = d_make_root(inode); |
| if (!sb->s_root) |
| goto failed; |
| return 0; |
| |
| failed: |
| shmem_put_super(sb); |
| return err; |
| } |
| |
| static struct kmem_cache *shmem_inode_cachep; |
| |
| static struct inode *shmem_alloc_inode(struct super_block *sb) |
| { |
| struct shmem_inode_info *info; |
| info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); |
| if (!info) |
| return NULL; |
| return &info->vfs_inode; |
| } |
| |
| static void shmem_destroy_callback(struct rcu_head *head) |
| { |
| struct inode *inode = container_of(head, struct inode, i_rcu); |
| kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); |
| } |
| |
| static void shmem_destroy_inode(struct inode *inode) |
| { |
| if (S_ISREG(inode->i_mode)) |
| mpol_free_shared_policy(&SHMEM_I(inode)->policy); |
| call_rcu(&inode->i_rcu, shmem_destroy_callback); |
| } |
| |
| static void shmem_init_inode(void *foo) |
| { |
| struct shmem_inode_info *info = foo; |
| inode_init_once(&info->vfs_inode); |
| } |
| |
| static int shmem_init_inodecache(void) |
| { |
| shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", |
| sizeof(struct shmem_inode_info), |
| 0, SLAB_PANIC, shmem_init_inode); |
| return 0; |
| } |
| |
| static void shmem_destroy_inodecache(void) |
| { |
| kmem_cache_destroy(shmem_inode_cachep); |
| } |
| |
| static const struct address_space_operations shmem_aops = { |
| .writepage = shmem_writepage, |
| .set_page_dirty = __set_page_dirty_no_writeback, |
| #ifdef CONFIG_TMPFS |
| .write_begin = shmem_write_begin, |
| .write_end = shmem_write_end, |
| #endif |
| .migratepage = migrate_page, |
| .error_remove_page = generic_error_remove_page, |
| }; |
| |
| static const struct file_operations shmem_file_operations = { |
| .mmap = shmem_mmap, |
| #ifdef CONFIG_TMPFS |
| .llseek = shmem_file_llseek, |
| .read = do_sync_read, |
| .write = do_sync_write, |
| .aio_read = shmem_file_aio_read, |
| .aio_write = generic_file_aio_write, |
| .fsync = noop_fsync, |
| .splice_read = shmem_file_splice_read, |
| .splice_write = generic_file_splice_write, |
| .fallocate = shmem_fallocate, |
| #endif |
| }; |
| |
| static const struct inode_operations shmem_inode_operations = { |
| .setattr = shmem_setattr, |
| #ifdef CONFIG_TMPFS_XATTR |
| .setxattr = shmem_setxattr, |
| .getxattr = shmem_getxattr, |
| .listxattr = shmem_listxattr, |
| .removexattr = shmem_removexattr, |
| .set_acl = simple_set_acl, |
| #endif |
| }; |
| |
| static const struct inode_operations shmem_dir_inode_operations = { |
| #ifdef CONFIG_TMPFS |
| .create = shmem_create, |
| .lookup = simple_lookup, |
| .link = shmem_link, |
| .unlink = shmem_unlink, |
| .symlink = shmem_symlink, |
| .mkdir = shmem_mkdir, |
| .rmdir = shmem_rmdir, |
| .mknod = shmem_mknod, |
| .rename = shmem_rename, |
| .tmpfile = shmem_tmpfile, |
| #endif |
| #ifdef CONFIG_TMPFS_XATTR |
| .setxattr = shmem_setxattr, |
| .getxattr = shmem_getxattr, |
| .listxattr = shmem_listxattr, |
| .removexattr = shmem_removexattr, |
| #endif |
| #ifdef CONFIG_TMPFS_POSIX_ACL |
| .setattr = shmem_setattr, |
| .set_acl = simple_set_acl, |
| #endif |
| }; |
| |
| static const struct inode_operations shmem_special_inode_operations = { |
| #ifdef CONFIG_TMPFS_XATTR |
| .setxattr = shmem_setxattr, |
| .getxattr = shmem_getxattr, |
| .listxattr = shmem_listxattr, |
| .removexattr = shmem_removexattr, |
| #endif |
| #ifdef CONFIG_TMPFS_POSIX_ACL |
| .setattr = shmem_setattr, |
| .set_acl = simple_set_acl, |
| #endif |
| }; |
| |
| static const struct super_operations shmem_ops = { |
| .alloc_inode = shmem_alloc_inode, |
| .destroy_inode = shmem_destroy_inode, |
| #ifdef CONFIG_TMPFS |
| .statfs = shmem_statfs, |
| .remount_fs = shmem_remount_fs, |
| .show_options = shmem_show_options, |
| #endif |
| .evict_inode = shmem_evict_inode, |
| .drop_inode = generic_delete_inode, |
| .put_super = shmem_put_super, |
| }; |
| |
| static const struct vm_operations_struct shmem_vm_ops = { |
| .fault = shmem_fault, |
| #ifdef CONFIG_NUMA |
| .set_policy = shmem_set_policy, |
| .get_policy = shmem_get_policy, |
| #endif |
| .remap_pages = generic_file_remap_pages, |
| }; |
| |
| static struct dentry *shmem_mount(struct file_system_type *fs_type, |
| int flags, const char *dev_name, void *data) |
| { |
| return mount_nodev(fs_type, flags, data, shmem_fill_super); |
| } |
| |
| static struct file_system_type shmem_fs_type = { |
| .owner = THIS_MODULE, |
| .name = "tmpfs", |
| .mount = shmem_mount, |
| .kill_sb = kill_litter_super, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| |
| int __init shmem_init(void) |
| { |
| int error; |
| |
| /* If rootfs called this, don't re-init */ |
| if (shmem_inode_cachep) |
| return 0; |
| |
| error = bdi_init(&shmem_backing_dev_info); |
| if (error) |
| goto out4; |
| |
| error = shmem_init_inodecache(); |
| if (error) |
| goto out3; |
| |
| error = register_filesystem(&shmem_fs_type); |
| if (error) { |
| printk(KERN_ERR "Could not register tmpfs\n"); |
| goto out2; |
| } |
| |
| shm_mnt = kern_mount(&shmem_fs_type); |
| if (IS_ERR(shm_mnt)) { |
| error = PTR_ERR(shm_mnt); |
| printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
| goto out1; |
| } |
| return 0; |
| |
| out1: |
| unregister_filesystem(&shmem_fs_type); |
| out2: |
| shmem_destroy_inodecache(); |
| out3: |
| bdi_destroy(&shmem_backing_dev_info); |
| out4: |
| shm_mnt = ERR_PTR(error); |
| return error; |
| } |
| |
| #else /* !CONFIG_SHMEM */ |
| |
| /* |
| * tiny-shmem: simple shmemfs and tmpfs using ramfs code |
| * |
| * This is intended for small system where the benefits of the full |
| * shmem code (swap-backed and resource-limited) are outweighed by |
| * their complexity. On systems without swap this code should be |
| * effectively equivalent, but much lighter weight. |
| */ |
| |
| static struct file_system_type shmem_fs_type = { |
| .name = "tmpfs", |
| .mount = ramfs_mount, |
| .kill_sb = kill_litter_super, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| |
| int __init shmem_init(void) |
| { |
| BUG_ON(register_filesystem(&shmem_fs_type) != 0); |
| |
| shm_mnt = kern_mount(&shmem_fs_type); |
| BUG_ON(IS_ERR(shm_mnt)); |
| |
| return 0; |
| } |
| |
| int shmem_unuse(swp_entry_t swap, struct page *page) |
| { |
| return 0; |
| } |
| |
| int shmem_lock(struct file *file, int lock, struct user_struct *user) |
| { |
| return 0; |
| } |
| |
| void shmem_unlock_mapping(struct address_space *mapping) |
| { |
| } |
| |
| void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
| { |
| truncate_inode_pages_range(inode->i_mapping, lstart, lend); |
| } |
| EXPORT_SYMBOL_GPL(shmem_truncate_range); |
| |
| #define shmem_vm_ops generic_file_vm_ops |
| #define shmem_file_operations ramfs_file_operations |
| #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) |
| #define shmem_acct_size(flags, size) 0 |
| #define shmem_unacct_size(flags, size) do {} while (0) |
| |
| #endif /* CONFIG_SHMEM */ |
| |
| /* common code */ |
| |
| static struct dentry_operations anon_ops = { |
| .d_dname = simple_dname |
| }; |
| |
| static struct file *__shmem_file_setup(const char *name, loff_t size, |
| unsigned long flags, unsigned int i_flags) |
| { |
| struct file *res; |
| struct inode *inode; |
| struct path path; |
| struct super_block *sb; |
| struct qstr this; |
| |
| if (IS_ERR(shm_mnt)) |
| return ERR_CAST(shm_mnt); |
| |
| if (size < 0 || size > MAX_LFS_FILESIZE) |
| return ERR_PTR(-EINVAL); |
| |
| if (shmem_acct_size(flags, size)) |
| return ERR_PTR(-ENOMEM); |
| |
| res = ERR_PTR(-ENOMEM); |
| this.name = name; |
| this.len = strlen(name); |
| this.hash = 0; /* will go */ |
| sb = shm_mnt->mnt_sb; |
| path.dentry = d_alloc_pseudo(sb, &this); |
| if (!path.dentry) |
| goto put_memory; |
| d_set_d_op(path.dentry, &anon_ops); |
| path.mnt = mntget(shm_mnt); |
| |
| res = ERR_PTR(-ENOSPC); |
| inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); |
| if (!inode) |
| goto put_dentry; |
| |
| inode->i_flags |= i_flags; |
| d_instantiate(path.dentry, inode); |
| inode->i_size = size; |
| clear_nlink(inode); /* It is unlinked */ |
| res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size)); |
| if (IS_ERR(res)) |
| goto put_dentry; |
| |
| res = alloc_file(&path, FMODE_WRITE | FMODE_READ, |
| &shmem_file_operations); |
| if (IS_ERR(res)) |
| goto put_dentry; |
| |
| return res; |
| |
| put_dentry: |
| path_put(&path); |
| put_memory: |
| shmem_unacct_size(flags, size); |
| return res; |
| } |
| |
| /** |
| * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be |
| * kernel internal. There will be NO LSM permission checks against the |
| * underlying inode. So users of this interface must do LSM checks at a |
| * higher layer. The one user is the big_key implementation. LSM checks |
| * are provided at the key level rather than the inode level. |
| * @name: name for dentry (to be seen in /proc/<pid>/maps |
| * @size: size to be set for the file |
| * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
| */ |
| struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags) |
| { |
| return __shmem_file_setup(name, size, flags, S_PRIVATE); |
| } |
| |
| /** |
| * shmem_file_setup - get an unlinked file living in tmpfs |
| * @name: name for dentry (to be seen in /proc/<pid>/maps |
| * @size: size to be set for the file |
| * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
| */ |
| struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) |
| { |
| return __shmem_file_setup(name, size, flags, 0); |
| } |
| EXPORT_SYMBOL_GPL(shmem_file_setup); |
| |
| /** |
| * shmem_zero_setup - setup a shared anonymous mapping |
| * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
| */ |
| int shmem_zero_setup(struct vm_area_struct *vma) |
| { |
| struct file *file; |
| loff_t size = vma->vm_end - vma->vm_start; |
| |
| file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
| if (IS_ERR(file)) |
| return PTR_ERR(file); |
| |
| if (vma->vm_file) |
| fput(vma->vm_file); |
| vma->vm_file = file; |
| vma->vm_ops = &shmem_vm_ops; |
| return 0; |
| } |
| |
| /** |
| * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. |
| * @mapping: the page's address_space |
| * @index: the page index |
| * @gfp: the page allocator flags to use if allocating |
| * |
| * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", |
| * with any new page allocations done using the specified allocation flags. |
| * But read_cache_page_gfp() uses the ->readpage() method: which does not |
| * suit tmpfs, since it may have pages in swapcache, and needs to find those |
| * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. |
| * |
| * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in |
| * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. |
| */ |
| struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, |
| pgoff_t index, gfp_t gfp) |
| { |
| #ifdef CONFIG_SHMEM |
| struct inode *inode = mapping->host; |
| struct page *page; |
| int error; |
| |
| BUG_ON(mapping->a_ops != &shmem_aops); |
| error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); |
| if (error) |
| page = ERR_PTR(error); |
| else |
| unlock_page(page); |
| return page; |
| #else |
| /* |
| * The tiny !SHMEM case uses ramfs without swap |
| */ |
| return read_cache_page_gfp(mapping, index, gfp); |
| #endif |
| } |
| EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |