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author | Jan Kara <jack@suse.cz> | 2012-04-25 21:15:53 +0200 |
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committer | Jan Kara <jack@suse.cz> | 2012-05-15 23:34:39 +0200 |
commit | a80b12c3d08dbbf15e6a551e481c32a2df4911f3 (patch) | |
tree | 364989f0fc990496820296b5fc6b655e29416c14 /fs/quota/dquot.c | |
parent | f9ef178412cab442719c9ffdc659933f5f2fa87e (diff) | |
download | linux-stable-a80b12c3d08dbbf15e6a551e481c32a2df4911f3.tar.gz linux-stable-a80b12c3d08dbbf15e6a551e481c32a2df4911f3.tar.bz2 linux-stable-a80b12c3d08dbbf15e6a551e481c32a2df4911f3.zip |
quota: Get rid of nested I_MUTEX_QUOTA locking subclass
So far i_mutex was ranking above dqonoff_mutex and i_mutex on quota files
was special and ranking below dqonoff_mutex (and several other locks).
However there's no real need for i_mutex on quota files to be special.
IO on quota files is serialized by dqio_mutex anyway so we don't need to
take i_mutex when writing to quota files. Other places where we take i_mutex
on quota file can accomodate standard i_mutex lock ranking, we only need
to change the lock ranking to be dqonoff_mutex > i_mutex which is a matter
of changing documentation because there's no place which would enforce
ordering in the other direction.
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/quota/dquot.c')
-rw-r--r-- | fs/quota/dquot.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 6e429fdda17d..10cbe841cb7e 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -116,15 +116,15 @@ * spinlock to internal buffers before writing. * * Lock ordering (including related VFS locks) is the following: - * i_mutex > dqonoff_sem > journal_lock > dqptr_sem > dquot->dq_lock > + * dqonoff_mutex > i_mutex > journal_lock > dqptr_sem > dquot->dq_lock > * dqio_mutex + * dqonoff_mutex > i_mutex comes from dquot_quota_sync, dquot_enable, etc. * The lock ordering of dqptr_sem imposed by quota code is only dqonoff_sem > * dqptr_sem. But filesystem has to count with the fact that functions such as * dquot_alloc_space() acquire dqptr_sem and they usually have to be called * from inside a transaction to keep filesystem consistency after a crash. Also * filesystems usually want to do some IO on dquot from ->mark_dirty which is * called with dqptr_sem held. - * i_mutex on quota files is special (it's below dqio_mutex) */ static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_list_lock); @@ -658,8 +658,7 @@ int dquot_quota_sync(struct super_block *sb, int type, int wait) continue; if (!sb_has_quota_active(sb, cnt)) continue; - mutex_lock_nested(&dqopt->files[cnt]->i_mutex, - I_MUTEX_QUOTA); + mutex_lock(&dqopt->files[cnt]->i_mutex); truncate_inode_pages(&dqopt->files[cnt]->i_data, 0); mutex_unlock(&dqopt->files[cnt]->i_mutex); } @@ -2037,8 +2036,7 @@ int dquot_disable(struct super_block *sb, int type, unsigned int flags) /* If quota was reenabled in the meantime, we have * nothing to do */ if (!sb_has_quota_loaded(sb, cnt)) { - mutex_lock_nested(&toputinode[cnt]->i_mutex, - I_MUTEX_QUOTA); + mutex_lock(&toputinode[cnt]->i_mutex); toputinode[cnt]->i_flags &= ~(S_IMMUTABLE | S_NOATIME | S_NOQUOTA); truncate_inode_pages(&toputinode[cnt]->i_data, @@ -2133,7 +2131,7 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id, /* We don't want quota and atime on quota files (deadlocks * possible) Also nobody should write to the file - we use * special IO operations which ignore the immutable bit. */ - mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA); + mutex_lock(&inode->i_mutex); oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA); inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE; @@ -2180,7 +2178,7 @@ out_file_init: iput(inode); out_lock: if (oldflags != -1) { - mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA); + mutex_lock(&inode->i_mutex); /* Set the flags back (in the case of accidental quotaon() * on a wrong file we don't want to mess up the flags) */ inode->i_flags &= ~(S_NOATIME | S_NOQUOTA | S_IMMUTABLE); |