fs: avoid softlockups in s_inodes iterators

BugLink: https://bugs.launchpad.net/bugs/1861929
[ Upstream commit 04646aebd30b99f2cfa0182435a2ec252fcb16d0 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index d31b6c72b47646fd8ae2ebd3746de307f8017fa0..dc1a1d5d825b48de17f3192f8d0c50829dd07885 100644 (file)
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -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);

diff --git a/fs/inode.c b/fs/inode.c
index 8a5c14630ff067a87aea5828d5023211472dd79c..d82ba21ce1650a995ca3743bd4fe8aa74f669a3d 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -673,6 +673,7 @@ 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);
@@ -695,6 +696,12 @@ 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);
 

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 2ecef6155fc0ded7d39e7e8b84b71a9356784a69..ac9eb273e28cd19a2651fbbe4d5733cc54ac50fa 100644 (file)
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -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);

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index d43212a60c8435c89161a8d7cdef1bb239f70bbb..204c0e381451b599d6c39be7df5ec00ee0186a22 100644 (file)
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -986,6 +986,7 @@ 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);