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: dae2f8ed7992 ("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>

diff --git a/fs/inode.c b/fs/inode.c
index 9d78c37..5eea991 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -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;

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8667d0c..8bde32c 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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);