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Btrfs: don't continue setting up space cache when enospc 

If we hit ENOSPC when setting up a space cache don't bother setting up any of
the other space cache's in this transaction, it'll just induce unnecessary
latency.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Josef Bacik 2015-10-01 12:55:18 -04:00 committed by Chris Mason
parent 4f4db2174d
commit 2968b1f48b
2 changed files with 20 additions and 0 deletions
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19
fs/btrfs/extent-tree.c
View File

@ -3402,6 +3402,15 @@ static int cache_save_setup(struct btrfs_block_group_cache *block_group,
}
spin_unlock(&block_group->lock);
/*
* We hit an ENOSPC when setting up the cache in this transaction, just
* skip doing the setup, we've already cleared the cache so we're safe.
*/
if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) {
ret = -ENOSPC;
goto out_put;
}
/*
* Try to preallocate enough space based on how big the block group is.
* Keep in mind this has to include any pinned space which could end up
@ -3422,8 +3431,18 @@ static int cache_save_setup(struct btrfs_block_group_cache *block_group,
ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
num_pages, num_pages,
&alloc_hint);
/*
* Our cache requires contiguous chunks so that we don't modify a bunch
* of metadata or split extents when writing the cache out, which means
* we can enospc if we are heavily fragmented in addition to just normal
* out of space conditions. So if we hit this just skip setting up any
* other block groups for this transaction, maybe we'll unpin enough
* space the next time around.
*/
if (!ret)
dcs = BTRFS_DC_SETUP;
else if (ret == -ENOSPC)
set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
btrfs_free_reserved_data_space(inode, num_pages);
out_put:

1
fs/btrfs/transaction.h
View File

@ -34,6 +34,7 @@ enum btrfs_trans_state {
#define BTRFS_TRANS_HAVE_FREE_BGS 0
#define BTRFS_TRANS_DIRTY_BG_RUN 1
#define BTRFS_TRANS_CACHE_ENOSPC 2
struct btrfs_transaction {
u64 transid;