This is a note to let you know that I've just added the patch titled
ovl: allow upperdir inside lowerdir
to the 5.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ovl-allow-upperdir-inside-lowerdir.patch
and it can be found in the queue-5.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 708fa01597fa002599756bf56a96d0de1677375c Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Date: Mon, 12 Apr 2021 12:00:37 +0200
Subject: ovl: allow upperdir inside lowerdir
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
commit 708fa01597fa002599756bf56a96d0de1677375c upstream.
Commit 146d62e5a586 ("ovl: detect overlapping layers") made sure we don't
have overlapping layers, but it also broke the arguably valid use case of
mount -olowerdir=/,upperdir=/subdir,..
where upperdir overlaps lowerdir on the same filesystem. This has been
causing regressions.
Revert the check, but only for the specific case where upperdir and/or
workdir are subdirectories of lowerdir. Any other overlap (e.g. lowerdir
is subdirectory of upperdir, etc) case is crazy, so leave the check in
place for those.
Overlaps are detected at lookup time too, so reverting the mount time check
should be safe.
Fixes: 146d62e5a586 ("ovl: detect overlapping layers")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.2
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/overlayfs/super.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1826,7 +1826,8 @@ out_err:
* - upper/work dir of any overlayfs instance
*/
static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs,
- struct dentry *dentry, const char *name)
+ struct dentry *dentry, const char *name,
+ bool is_lower)
{
struct dentry *next = dentry, *parent;
int err = 0;
@@ -1838,7 +1839,7 @@ static int ovl_check_layer(struct super_
/* Walk back ancestors to root (inclusive) looking for traps */
while (!err && parent != next) {
- if (ovl_lookup_trap_inode(sb, parent)) {
+ if (is_lower && ovl_lookup_trap_inode(sb, parent)) {
err = -ELOOP;
pr_err("overlapping %s path\n", name);
} else if (ovl_is_inuse(parent)) {
@@ -1864,7 +1865,7 @@ static int ovl_check_overlapping_layers(
if (ovl_upper_mnt(ofs)) {
err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root,
- "upperdir");
+ "upperdir", false);
if (err)
return err;
@@ -1875,7 +1876,8 @@ static int ovl_check_overlapping_layers(
* workbasedir. In that case, we already have their traps in
* inode cache and we will catch that case on lookup.
*/
- err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir");
+ err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir",
+ false);
if (err)
return err;
}
@@ -1883,7 +1885,7 @@ static int ovl_check_overlapping_layers(
for (i = 1; i < ofs->numlayer; i++) {
err = ovl_check_layer(sb, ofs,
ofs->layers[i].mnt->mnt_root,
- "lowerdir");
+ "lowerdir", true);
if (err)
return err;
}
Patches currently in stable-queue which might be from mszeredi@xxxxxxxxxx are
queue-5.12/ovl-fix-leaked-dentry.patch
queue-5.12/ovl-allow-upperdir-inside-lowerdir.patch
