Btrfs: make find_first_extent_bit be able to cache any state

Right now the only caller of find_first_extent_bit() that is interested
in caching extent states (transaction or log commit), never gets an extent
state cached. This is because find_first_extent_bit() only caches states
that have at least one of the flags EXTENT_IOBITS or EXTENT_BOUNDARY, and
the transaction/log commit caller always passes a tree that doesn't have
ever extent states with any of those flags (they can only have one of the
following flags: EXTENT_DIRTY, EXTENT_NEW or EXTENT_NEED_WAIT).

This change together with the following one in the patch series (titled
"Btrfs: avoid returning -ENOMEM in convert_extent_bit() too early") will
help reduce significantly the chances of calls to convert_extent_bit()
fail with -ENOMEM when called from the transaction/log commit code.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 04dbc800c209..16c704b68704 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -883,6 +883,7 @@ int btrfs_write_marked_extents(struct btrfs_root *root,
                         werr = err;
                 else if (wait_writeback)
                         werr = filemap_fdatawait_range(mapping, start, end);
+                free_extent_state(cached_state);
                 cached_state = NULL;
                 cond_resched();
                 start = end + 1;
@@ -927,6 +928,8 @@ int btrfs_wait_marked_extents(struct btrfs_root *root,
                         err = filemap_fdatawait_range(mapping, start, end);
                 if (err)
                         werr = err;
+                free_extent_state(cached_state);
+                cached_state = NULL;
                 cond_resched();
                 start = end + 1;
         }