Commit 88149082 authored Dec 08, 2020 by Hao Li Committed by Al Viro Dec 10, 2020

fs: Handle I_DONTCACHE in iput_final() instead of generic_drop_inode()

If generic_drop_inode() returns true, it means iput_final() can evict
this inode regardless of whether it is dirty or not. If we check
I_DONTCACHE in generic_drop_inode(), any inode with this bit set will be
evicted unconditionally. This is not the desired behavior because
I_DONTCACHE only means the inode shouldn't be cached on the LRU list.
As for whether we need to evict this inode, this is what
generic_drop_inode() should do. This patch corrects the usage of
I_DONTCACHE.

This patch was proposed in [1].

[1]: https://lore.kernel.org/linux-fsdevel/20200831003407.GE12096@dread.disaster.area/



Fixes: dae2f8ed ("fs: Lift XFS_IDONTCACHE to the VFS layer")
Signed-off-by: Hao Li <lihao2018.fnst@cn.fujitsu.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent edf7ddbf

fs/inode.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1627,7 +1627,9 @@ static void iput_final(struct inode *inode)
		else
		drop = generic_drop_inode(inode);

		if (!drop && (sb->s_flags & SB_ACTIVE)) {
		if (!drop &&
		!(inode->i_state & I_DONTCACHE) &&
		(sb->s_flags & SB_ACTIVE)) {
		inode_add_lru(inode);
		spin_unlock(&inode->i_lock);
		return;

include/linux/fs.h

+1 −2

Original line number	Diff line number	Diff line
		@@ -2878,8 +2878,7 @@ extern int inode_needs_sync(struct inode *inode);
		extern int generic_delete_inode(struct inode *inode);
		static inline int generic_drop_inode(struct inode *inode)
		{
		return !inode->i_nlink \|\| inode_unhashed(inode) \|\|
		(inode->i_state & I_DONTCACHE);
		return !inode->i_nlink \|\| inode_unhashed(inode);
		}
		extern void d_mark_dontcache(struct inode *inode);

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