exofs: Define on-disk per-inode optional layout attribute
* Layouts describe the way a file is spread on multiple devices.
The layout information is stored in the objects attribute introduced
in this patch.
* There can be multiple generating function for the layout.
Currently defined:
- No attribute present - use below moving-window on global
device table, all devices.
(This is the only one currently used in exofs)
- an obj_id generated moving window - the obj_id is a randomizing
factor in the otherwise global map layout.
- An explicit layout stored, including a data_map and a device
index list.
- More might be defined in future ...
* There are two attributes defined of the same structure:
A-data-files-layout - This layout is used by data-files. If present
at a directory, all files of that directory will
be created with this layout.
A-meta-data-layout - This layout is used by a directory and other
meta-data information. Also inherited at creation
of subdirectories.
* At creation time inodes are created with the layout specified above.
A usermode utility may change the creation layout on a give directory
or file. Which in the case of directories, will also apply to newly
created files/subdirectories, children of that directory.
In the simple unaltered case of a newly created exofs, no layout
attributes are present, and all layouts adhere to the layout specified
at the device-table.
* In case of a future file system loaded in an old exofs-driver.
At iget(), the generating_function is inspected and if not supported
will return an IO error to the application and the inode will not
be loaded. So not to damage any data.
Note: After this patch we do not yet support any type of layout
only the RAID0 patch that enables striping at the super-block
level will add support for RAID0 layouts above. This way we
are past and future compatible and fully bisectable.
* Access to the device table is done by an accessor since
it will change according to above information.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/fs/exofs/ios.c b/fs/exofs/ios.c
index 4f67931..2b81f99 100644
--- a/fs/exofs/ios.c
+++ b/fs/exofs/ios.c
@@ -107,6 +107,19 @@
}
}
+unsigned exofs_layout_od_id(struct exofs_layout *layout,
+ osd_id obj_no, unsigned layout_index)
+{
+ return layout_index;
+}
+
+static inline struct osd_dev *exofs_ios_od(struct exofs_io_state *ios,
+ unsigned layout_index)
+{
+ return ios->layout->s_ods[
+ exofs_layout_od_id(ios->layout, ios->obj.id, layout_index)];
+}
+
static void _sync_done(struct exofs_io_state *ios, void *p)
{
struct completion *waiting = p;
@@ -242,7 +255,7 @@
for (i = 0; i < ios->layout->s_numdevs; i++) {
struct osd_request *or;
- or = osd_start_request(ios->layout->s_ods[i], GFP_KERNEL);
+ or = osd_start_request(exofs_ios_od(ios, i), GFP_KERNEL);
if (unlikely(!or)) {
EXOFS_ERR("%s: osd_start_request failed\n", __func__);
ret = -ENOMEM;
@@ -266,7 +279,7 @@
for (i = 0; i < ios->layout->s_numdevs; i++) {
struct osd_request *or;
- or = osd_start_request(ios->layout->s_ods[i], GFP_KERNEL);
+ or = osd_start_request(exofs_ios_od(ios, i), GFP_KERNEL);
if (unlikely(!or)) {
EXOFS_ERR("%s: osd_start_request failed\n", __func__);
ret = -ENOMEM;
@@ -290,7 +303,7 @@
for (i = 0; i < ios->layout->s_numdevs; i++) {
struct osd_request *or;
- or = osd_start_request(ios->layout->s_ods[i], GFP_KERNEL);
+ or = osd_start_request(exofs_ios_od(ios, i), GFP_KERNEL);
if (unlikely(!or)) {
EXOFS_ERR("%s: osd_start_request failed\n", __func__);
ret = -ENOMEM;
@@ -361,7 +374,7 @@
unsigned first_dev = (unsigned)ios->obj.id;
first_dev %= ios->layout->s_numdevs;
- or = osd_start_request(ios->layout->s_ods[first_dev], GFP_KERNEL);
+ or = osd_start_request(exofs_ios_od(ios, first_dev), GFP_KERNEL);
if (unlikely(!or)) {
EXOFS_ERR("%s: osd_start_request failed\n", __func__);
return -ENOMEM;
@@ -442,7 +455,7 @@
for (i = 0; i < sbi->layout.s_numdevs; i++) {
struct osd_request *or;
- or = osd_start_request(sbi->layout.s_ods[i], GFP_KERNEL);
+ or = osd_start_request(exofs_ios_od(ios, i), GFP_KERNEL);
if (unlikely(!or)) {
EXOFS_ERR("%s: osd_start_request failed\n", __func__);
ret = -ENOMEM;
