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Commit d003fb70 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
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[PATCH] remove sb->s_files and file_list_lock usage in dquot.c 



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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fb58b731

fs/dquot.c

+18 −14
Original line number Diff line number Diff line
@@ -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();

	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);

			dput(dentry);

		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) */