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[PATCH] remove sb->s_files and file_list_lock usage in dquot.c

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Iterate over sb->s_inodes instead of sb->s_files in add_dquot_ref.  This
reduces list search and lock hold time aswell as getting rid of one of the
few uses of file_list_lock which Ingo identified as a scalability problem.

Previously we called dq_op->initialize for every inode handing of a
writeable file that wasn't initialized before.  Now we're calling it for
every inode that has a non-zero i_writecount, aka a writeable file
descriptor refering to it.

Thanks a lot to Jan Kara for running this patch through his quota test
harness.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Hellwig 2007-02-12 00:51:58 -08:00 committed by Linus Torvalds
parent fb58b7316a
commit d003fb70fd
1 changed files with 18 additions and 14 deletions
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32
fs/dquot.c
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@ -688,23 +688,27 @@ static int dqinit_needed(struct inode *inode, int type)
/* This routine is guarded by dqonoff_mutex mutex */
static void add_dquot_ref(struct super_block *sb, int type)
{
struct list_head *p;
struct inode *inode;
restart:
file_list_lock();
list_for_each(p, &sb->s_files) {
struct file *filp = list_entry(p, struct file, f_u.fu_list);
struct inode *inode = filp->f_path.dentry->d_inode;
if (filp->f_mode & FMODE_WRITE && dqinit_needed(inode, type)) {
struct dentry *dentry = dget(filp->f_path.dentry);
file_list_unlock();
sb->dq_op->initialize(inode, type);
dput(dentry);
/* As we may have blocked we had better restart... */
goto restart;
}
spin_lock(&inode_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
if (!atomic_read(&inode->i_writecount))
continue;
if (!dqinit_needed(inode, type))
continue;
if (inode->i_state & (I_FREEING|I_WILL_FREE))
continue;
__iget(inode);
spin_unlock(&inode_lock);
sb->dq_op->initialize(inode, type);
iput(inode);
/* As we may have blocked we had better restart... */
goto restart;
}
file_list_unlock();
spin_unlock(&inode_lock);
}
/* Return 0 if dqput() won't block (note that 1 doesn't necessarily mean blocking) */