Some features can only work when all layers are on the same fs.
Check that during mount time, so features can test it later.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/ovl_entry.h | 3 ++-
fs/overlayfs/super.c | 7 +++++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 12c4922..0e159c3 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -27,7 +27,8 @@ struct ovl_fs {
struct ovl_config config;
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
- bool tmpfile;
+ bool tmpfile; /* upper supports O_TMPFILE */
+ bool samefs; /* all layers on same fs */
wait_queue_head_t copyup_wq;
};
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 6d9766f..b8a83e8 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -876,6 +876,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
if (ufs->lower_mnt == NULL)
goto out_put_workdir;
+
+ ufs->samefs = true;
for (i = 0; i < numlower; i++) {
struct vfsmount *mnt = clone_private_mount(&stack[i]);
@@ -892,6 +894,11 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ufs->lower_mnt[ufs->numlower] = mnt;
ufs->numlower++;
+
+ /* Check if all layers on same sb */
+ if ((ufs->upper_mnt && ufs->upper_mnt->mnt_sb != mnt->mnt_sb) ||
+ (i > 0 && ufs->lower_mnt[0]->mnt_sb != mnt->mnt_sb))
+ ufs->samefs = false;
}
/* If the upper fs is nonexistent, we mark overlayfs r/o too */
--
2.7.4
--
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