diff options
author | Frederic Weisbecker <fweisbec@gmail.com> | 2009-05-08 01:48:44 +0400 |
---|---|---|
committer | Frederic Weisbecker <fweisbec@gmail.com> | 2009-09-14 09:18:16 +0400 |
commit | 26931309a47747fd31b2ef029c29d47794c2d93d (patch) | |
tree | 85b3ba9ee14c6d90243e4590af60e7ef3e72c5ff /fs/reiserfs | |
parent | d663af807d8bb226394cb7e02f4665f6141a8140 (diff) | |
download | linux-26931309a47747fd31b2ef029c29d47794c2d93d.tar.xz |
kill-the-bkl/reiserfs: lock only once on reiserfs_get_block()
reiserfs_get_block() is one of these sites where the write lock might
be acquired recursively.
It's a particular problem because this function is called very often.
It's a hot spot which needs to reschedule() periodically while converting
direct items to indirect ones because it can take some time.
Then if we are applying the write lock release/reacquire pattern on
schedule() here, it may not produce the desired effect since we may have
locked in more than one depth.
The solution is to use reiserfs_write_lock_once() which won't try
to reacquire the lock recursively. Then the lock will be *really*
released before schedule().
Also, we only release the lock if TIF_NEED_RESCHED is set to not
create wasteful numerous contentions.
[ Impact: fix a too long holded lock case in reiserfs_get_block() ]
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'fs/reiserfs')
-rw-r--r-- | fs/reiserfs/inode.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c index cc70b56bf6f2..6114050f342e 100644 --- a/fs/reiserfs/inode.c +++ b/fs/reiserfs/inode.c @@ -605,6 +605,7 @@ int reiserfs_get_block(struct inode *inode, sector_t block, __le32 *item; int done; int fs_gen; + int lock_depth; struct reiserfs_transaction_handle *th = NULL; /* space reserved in transaction batch: . 3 balancings in direct->indirect conversion @@ -620,11 +621,11 @@ int reiserfs_get_block(struct inode *inode, sector_t block, loff_t new_offset = (((loff_t) block) << inode->i_sb->s_blocksize_bits) + 1; - reiserfs_write_lock(inode->i_sb); + lock_depth = reiserfs_write_lock_once(inode->i_sb); version = get_inode_item_key_version(inode); if (!file_capable(inode, block)) { - reiserfs_write_unlock(inode->i_sb); + reiserfs_write_unlock_once(inode->i_sb, lock_depth); return -EFBIG; } @@ -636,7 +637,7 @@ int reiserfs_get_block(struct inode *inode, sector_t block, /* find number of block-th logical block of the file */ ret = _get_block_create_0(inode, block, bh_result, create | GET_BLOCK_READ_DIRECT); - reiserfs_write_unlock(inode->i_sb); + reiserfs_write_unlock_once(inode->i_sb, lock_depth); return ret; } /* @@ -754,7 +755,7 @@ int reiserfs_get_block(struct inode *inode, sector_t block, if (!dangle && th) retval = reiserfs_end_persistent_transaction(th); - reiserfs_write_unlock(inode->i_sb); + reiserfs_write_unlock_once(inode->i_sb, lock_depth); /* the item was found, so new blocks were not added to the file ** there is no need to make sure the inode is updated with this @@ -1005,9 +1006,11 @@ int reiserfs_get_block(struct inode *inode, sector_t block, * long time. reschedule if needed and also release the write * lock for others. */ - reiserfs_write_unlock(inode->i_sb); - cond_resched(); - reiserfs_write_lock(inode->i_sb); + if (need_resched()) { + reiserfs_write_unlock_once(inode->i_sb, lock_depth); + schedule(); + lock_depth = reiserfs_write_lock_once(inode->i_sb); + } retval = search_for_position_by_key(inode->i_sb, &key, &path); if (retval == IO_ERROR) { @@ -1042,7 +1045,7 @@ int reiserfs_get_block(struct inode *inode, sector_t block, retval = err; } - reiserfs_write_unlock(inode->i_sb); + reiserfs_write_unlock_once(inode->i_sb, lock_depth); reiserfs_check_path(&path); return retval; } |