[PATCH] remove sb->s_files and file_list_lock usage in dquot.c (d003fb70) · Commits · 戴 / test

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>

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) */

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