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Btrfs: avoid deadlocks during reservations in btrfs_truncate_block 

The new enospc code makes it possible to deadlock if we don't use
FLUSH_LIMIT during reservations inside a transaction.  This enforces
the correct flush type to avoid both deadlocks and assertions

Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
This commit is contained in:
Josef Bacik 2016-07-20 16:48:45 -07:00 committed by Chris Mason
parent 24502ebb60
commit bac357dcec
1 changed files with 5 additions and 0 deletions
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5
fs/btrfs/extent-tree.c
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@ -5939,10 +5939,15 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
* the middle of a transaction commit. We also don't need the delalloc
* mutex since we won't race with anybody. We need this mostly to make
* lockdep shut its filthy mouth.
*
* If we have a transaction open (can happen if we call truncate_block
* from truncate), then we need FLUSH_LIMIT so we don't deadlock.
*/
if (btrfs_is_free_space_inode(inode)) {
flush = BTRFS_RESERVE_NO_FLUSH;
delalloc_lock = false;
} else if (current->journal_info) {
flush = BTRFS_RESERVE_FLUSH_LIMIT;
}
if (flush != BTRFS_RESERVE_NO_FLUSH &&