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authorIan Kent <raven@themaw.net>2023-08-06 03:26:49 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-08-12 13:05:47 +0200
commit0559f63057f927d298d68294d6ff77ce09b99255 (patch)
treec979d4f746f7d9e8d308b52cb8c57dd199193ad9 /fs/kernfs
parentdocs: stable-kernel-rules: mention that regressions must be prevented (diff)
downloadlinux-0559f63057f927d298d68294d6ff77ce09b99255.tar.xz
linux-0559f63057f927d298d68294d6ff77ce09b99255.zip
kernfs: fix missing kernfs_iattr_rwsem locking
When the kernfs_iattr_rwsem was introduced a case was missed. The update of the kernfs directory node child count was also protected by the kernfs_rwsem and needs to be included in the change so that the child count (and so the inode n_link attribute) does not change while holding the rwsem for read. Fixes: 9caf69614225 ("kernfs: Introduce separate rwsem to protect inode attributes.") Cc: stable <stable@kernel.org> Signed-off-by: Ian Kent <raven@themaw.net> Reviewed-By: Imran Khan <imran.f.khan@oracle.com> Acked-by: Miklos Szeredi <mszeredi@redhat.com> Cc: Anders Roxell <anders.roxell@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Eric Sandeen <sandeen@sandeen.net> Link: https://lore.kernel.org/r/169128520941.68052.15749253469930138901.stgit@donald.themaw.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs')
-rw-r--r--fs/kernfs/dir.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 5a1a4af9d3d2..bf243015834e 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -383,9 +383,11 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
rb_insert_color(&kn->rb, &kn->parent->dir.children);
/* successfully added, account subdir number */
+ down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs++;
kernfs_inc_rev(kn->parent);
+ up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
return 0;
}
@@ -408,9 +410,11 @@ static bool kernfs_unlink_sibling(struct kernfs_node *kn)
if (RB_EMPTY_NODE(&kn->rb))
return false;
+ down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs--;
kernfs_inc_rev(kn->parent);
+ up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
rb_erase(&kn->rb, &kn->parent->dir.children);
RB_CLEAR_NODE(&kn->rb);