st_ino returned by stat(2) for dirs on non-samefs is the non persistent
overlay i_ino. Update the dir cache with volatile overlay i_ino values.
Overlay dir cache and inode cache may get out of sync after child inodes
exit and re-enter inode cache. This means that user may see inconsistent
st_ino/d_ino, but user can already see inconsistent st_ino of same object
in different times, so this is better than nothing.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/readdir.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 4f2479b6ef91..4ec95806285e 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -120,6 +120,10 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
if (!rdd->dentry)
return false;
+ /* Always recalc d_ino from i_ino for dir on non-samefs */
+ if (p->type == DT_DIR && !ovl_same_sb(rdd->dentry->d_sb))
+ return true;
+
/* Always recalc d_ino for parent */
if (strcmp(p->name, "..") == 0)
return true;
@@ -459,9 +463,6 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
u64 ino = p->real_ino;
int err = 0;
- if (!ovl_same_sb(dir->d_sb))
- goto out;
-
if (p->name[0] == '.') {
if (p->len == 1) {
this = dget(dir);
@@ -484,6 +485,19 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
}
get:
+ /*
+ * st_ino for dirs on non-samefs is the non persistent overlay i_ino.
+ * Update the dir cache with volatile overlay i_ino, even though
+ * dir cache and inode cache may get out of sync after child inodes
+ * exit and re-enter inode cache. This means that user may see
+ * inconsistent st_ino/d_ino, but user can already see inconsistent
+ * st_ino of same object in different times.
+ */
+ if (p->type == DT_DIR && !ovl_same_sb(dir->d_sb)) {
+ ino = this->d_inode->i_ino;
+ goto out;
+ }
+
type = ovl_path_type(this);
if (OVL_TYPE_ORIGIN(type)) {
struct kstat stat;
@@ -494,7 +508,8 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
if (err)
goto fail;
- WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
+ if (ovl_same_sb(dir->d_sb))
+ WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
ino = stat.ino;
}
--
2.7.4
--
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