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Commit 29cb4859 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

writeback: fix pin_sb_for_writeback 



We need to check for s_instances to make sure we don't bother working
against a filesystem that is beeing unmounted, and we need to call
put_super to make sure a superblock is freed when we race against
umount.  Also no need to keep sb_lock after we got a reference on it.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 334132ae

fs/fs-writeback.c

+10 −8
Original line number Diff line number Diff line
@@ -534,19 +534,21 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 
static bool pin_sb_for_writeback(struct super_block *sb)

{

	spin_lock(&sb_lock);

	if (list_empty(&sb->s_instances)) {

		spin_unlock(&sb_lock);

		return false;

	}



	sb->s_count++;

	if (down_read_trylock(&sb->s_umount)) {

		if (sb->s_root) {

	spin_unlock(&sb_lock);



	if (down_read_trylock(&sb->s_umount)) {

		if (sb->s_root)

			return true;

		}

		/*

		 * umounted, drop rwsem again and fall through to failure

		 */

		up_read(&sb->s_umount);

	}

	sb->s_count--;

	spin_unlock(&sb_lock);



	put_super(sb);

	return false;

}