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fs: avoid softlockups in s_inodes iterators

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

Previous efforts were made in 2 functions, see:

c27d82f fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
ac05fbb 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: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Eric Sandeen 2019-12-06 10:54:23 -06:00 committed by Al Viro
parent e0ff126ee7
commit 04646aebd3
4 changed files with 10 additions and 1 deletions
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2
fs/drop_caches.c
View File

@ -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);

7
fs/inode.c
View File

@ -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);

1
fs/notify/fsnotify.c
View File

@ -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);

1
fs/quota/dquot.c
View File

@ -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);