On Thu 02-08-12 21:36:04, Jeff Mahoney wrote: > The BKL push-down for reiserfs made lock recursion a special case that needs > to be handled explicitly. One of the cases that was unhandled is dropping > the quota during inode eviction. Both reiserfs_evict_inode and > reiserfs_write_dquot take the write lock, but when the journal lock is > taken it only drops one the references. The locking rules are that the journal > lock be acquired before the write lock so leaving the reference open leads > to a ABBA deadlock. > > This patch pushes the unlock up before clear_inode and avoids the recursive > locking. > > Another ABBA situation can occur when the write lock is dropped while reading > the bitmap buffer while in the quota code. When the lock is reacquired, it > will deadlock against dquot->dq_lock and dqopt->dqio_mutex in the dquot_acquire > path. It's safe to retain the lock across the read and should be cached under > write load. > > Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx> Yeah, the patch looks good. Since we don't have reiserfs maintainer, I guess I'll push this through my tree. Honza > --- > fs/reiserfs/bitmap.c | 2 -- > fs/reiserfs/inode.c | 2 +- > 2 files changed, 1 insertion(+), 3 deletions(-) > > --- a/fs/reiserfs/bitmap.c > +++ b/fs/reiserfs/bitmap.c > @@ -1334,9 +1334,7 @@ struct buffer_head *reiserfs_read_bitmap > else if (bitmap == 0) > block = (REISERFS_DISK_OFFSET_IN_BYTES >> sb->s_blocksize_bits) + 1; > > - reiserfs_write_unlock(sb); > bh = sb_bread(sb, block); > - reiserfs_write_lock(sb); > if (bh == NULL) > reiserfs_warning(sb, "sh-2029: %s: bitmap block (#%u) " > "reading failed", __func__, block); > --- a/fs/reiserfs/inode.c > +++ b/fs/reiserfs/inode.c > @@ -76,10 +76,10 @@ void reiserfs_evict_inode(struct inode * > ; > } > out: > + reiserfs_write_unlock_once(inode->i_sb, depth); > clear_inode(inode); /* note this must go after the journal_end to prevent deadlock */ > dquot_drop(inode); > inode->i_blocks = 0; > - reiserfs_write_unlock_once(inode->i_sb, depth); > return; > > no_delete: > > -- > Jeff Mahoney > SUSE Labs -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
