xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Btrfs: fix enospc problems with delalloc

Browse Source 
So I had this brilliant idea to use atomic counters for outstanding and reserved
extents, but this turned out to be a bad idea.  Consider this where we have 1
outstanding extent and 1 reserved extent

Reserver				Releaser
					atomic_dec(outstanding) now 0
atomic_read(outstanding)+1 get 1
atomic_read(reserved) get 1
don't actually reserve anything because
they are the same
					atomic_cmpxchg(reserved, 1, 0)
atomic_inc(outstanding)
atomic_add(0, reserved)
					free reserved space for 1 extent

Then the reserver now has no actual space reserved for it, and when it goes to
finish the ordered IO it won't have enough space to do it's allocation and you
get those lovely warnings.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Josef Bacik
2011-07-15 15:16:44 +00:00
committed by Chris Mason
parent a599142806
commit 9e0baf60de
6 changed files with 86 additions and 60 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
fs/btrfs/file.c
View File

@@ -1239,9 +1239,11 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
* managed to copy.
*/
if (num_pages > dirty_pages) {
if (copied > 0)
atomic_inc(
&BTRFS_I(inode)->outstanding_extents);
if (copied > 0) {
spin_lock(&BTRFS_I(inode)->lock);
BTRFS_I(inode)->outstanding_extents++;
spin_unlock(&BTRFS_I(inode)->lock);
}
btrfs_delalloc_release_space(inode,
(num_pages - dirty_pages) <<
PAGE_CACHE_SHIFT);