From a80b12c3d08dbbf15e6a551e481c32a2df4911f3 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 25 Apr 2012 21:15:53 +0200 Subject: [PATCH] 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 --- fs/quota/dquot.c | 14 ++++++-------- 1 file 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); -- 2.34.1