NTFS: - Modify ->readpage and ->writepage (fs/ntfs/aops.c) so they detect
and handle the case where an attribute is converted from resident
to non-resident by a concurrent file write.
- Reorder some operations when converting an attribute from resident
to non-resident (fs/ntfs/attrib.c) so it is safe wrt concurrent
->readpage and ->writepage.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 2a7cba2..6241c4c 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -355,6 +355,7 @@
u32 attr_len;
int err = 0;
+retry_readpage:
BUG_ON(!PageLocked(page));
/*
* This can potentially happen because we clear PageUptodate() during
@@ -408,6 +409,14 @@
err = PTR_ERR(mrec);
goto err_out;
}
+ /*
+ * If a parallel write made the attribute non-resident, drop the mft
+ * record and retry the readpage.
+ */
+ if (unlikely(NInoNonResident(ni))) {
+ unmap_mft_record(base_ni);
+ goto retry_readpage;
+ }
ctx = ntfs_attr_get_search_ctx(base_ni, mrec);
if (unlikely(!ctx)) {
err = -ENOMEM;
@@ -1248,6 +1257,7 @@
u32 attr_len;
int err;
+retry_writepage:
BUG_ON(!PageLocked(page));
i_size = i_size_read(vi);
/* Is the page fully outside i_size? (truncate in progress) */
@@ -1338,6 +1348,14 @@
ctx = NULL;
goto err_out;
}
+ /*
+ * If a parallel write made the attribute non-resident, drop the mft
+ * record and retry the writepage.
+ */
+ if (unlikely(NInoNonResident(ni))) {
+ unmap_mft_record(base_ni);
+ goto retry_writepage;
+ }
ctx = ntfs_attr_get_search_ctx(base_ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
