Commit 04646aeb authored by Eric Sandeen's avatar Eric Sandeen Committed by Al Viro
Browse files

fs: avoid softlockups in s_inodes iterators 



Anything that walks all inodes on sb->s_inodes list without rescheduling
risks softlockups.

Previous efforts were made in 2 functions, see:

c27d82f5 fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
ac05fbb4 inode: don't softlockup when evicting inodes

but there hasn't been an audit of all walkers, so do that now.  This
also consistently moves the cond_resched() calls to the bottom of each
loop in cases where it already exists.

One loop remains: remove_dquot_ref(), because I'm not quite sure how
to deal with that one w/o taking the i_lock.

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e0ff126e

fs/drop_caches.c

+1 −1
Original line number Diff line number Diff line
@@ -35,11 +35,11 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused) 
		spin_unlock(&inode->i_lock);

		spin_unlock(&sb->s_inode_list_lock);



		cond_resched();

		invalidate_mapping_pages(inode->i_mapping, 0, -1);

		iput(toput_inode);

		toput_inode = inode;



		cond_resched();

		spin_lock(&sb->s_inode_list_lock);

	}

	spin_unlock(&sb->s_inode_list_lock);

fs/inode.c

+7 −0
Original line number Diff line number Diff line
@@ -676,6 +676,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) 
	struct inode *inode, *next;

	LIST_HEAD(dispose);



again:

	spin_lock(&sb->s_inode_list_lock);

	list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {

		spin_lock(&inode->i_lock);
@@ -698,6 +699,12 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty) 
		inode_lru_list_del(inode);

		spin_unlock(&inode->i_lock);

		list_add(&inode->i_lru, &dispose);

		if (need_resched()) {

			spin_unlock(&sb->s_inode_list_lock);

			cond_resched();

			dispose_list(&dispose);

			goto again;

		}

	}

	spin_unlock(&sb->s_inode_list_lock);

fs/notify/fsnotify.c

+1 −0
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ static void fsnotify_unmount_inodes(struct super_block *sb) 


		iput_inode = inode;



		cond_resched();

		spin_lock(&sb->s_inode_list_lock);

	}

	spin_unlock(&sb->s_inode_list_lock);

fs/quota/dquot.c

+1 −0
Original line number Diff line number Diff line
@@ -984,6 +984,7 @@ static int add_dquot_ref(struct super_block *sb, int type) 
		 * later.

		 */

		old_inode = inode;

		cond_resched();

		spin_lock(&sb->s_inode_list_lock);

	}

	spin_unlock(&sb->s_inode_list_lock);

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