ovl: generalize the lower_fs[] array
Rename lower_fs[] array to fs[], extend its size by one and use index fsid
(instead of fsid-1) to access the fs[] array.
Initialize fs[0] with upper fs values. fsid 0 is reserved even with lower
only overlay, so fs[0] remains null in this case.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 8f08313..d7c406d 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -228,10 +228,11 @@ static void ovl_free_fs(struct ovl_fs *ofs)
iput(ofs->layers[i].trap);
mntput(ofs->layers[i].mnt);
}
- for (i = 0; i < ofs->numlowerfs; i++)
- free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
kfree(ofs->layers);
- kfree(ofs->lower_fs);
+ /* fs[0].pseudo_dev is either null or real upper st_dev */
+ for (i = 1; i < ofs->numfs; i++)
+ free_anon_bdev(ofs->fs[i].pseudo_dev);
+ kfree(ofs->fs);
kfree(ofs->config.lowerdir);
kfree(ofs->config.upperdir);
@@ -1259,7 +1260,7 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
if (!ofs->config.nfs_export && !ofs->upper_mnt)
return true;
- for (i = 0; i < ofs->numlowerfs; i++) {
+ for (i = 1; i < ofs->numfs; i++) {
/*
* We use uuid to associate an overlay lower file handle with a
* lower layer, so we can accept lower fs with null uuid as long
@@ -1267,8 +1268,8 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
* if we detect multiple lower fs with the same uuid, we
* disable lower file handle decoding on all of them.
*/
- if (uuid_equal(&ofs->lower_fs[i].sb->s_uuid, uuid)) {
- ofs->lower_fs[i].bad_uuid = true;
+ if (uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
+ ofs->fs[i].bad_uuid = true;
return false;
}
}
@@ -1284,13 +1285,9 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
int err;
bool bad_uuid = false;
- /* fsid 0 is reserved for upper fs even with non upper overlay */
- if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb)
- return 0;
-
- for (i = 0; i < ofs->numlowerfs; i++) {
- if (ofs->lower_fs[i].sb == sb)
- return i + 1;
+ for (i = 0; i < ofs->numfs; i++) {
+ if (ofs->fs[i].sb == sb)
+ return i;
}
if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) {
@@ -1311,12 +1308,11 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
return err;
}
- ofs->lower_fs[ofs->numlowerfs].sb = sb;
- ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev;
- ofs->lower_fs[ofs->numlowerfs].bad_uuid = bad_uuid;
- ofs->numlowerfs++;
+ ofs->fs[ofs->numfs].sb = sb;
+ ofs->fs[ofs->numfs].pseudo_dev = dev;
+ ofs->fs[ofs->numfs].bad_uuid = bad_uuid;
- return ofs->numlowerfs;
+ return ofs->numfs++;
}
static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
@@ -1331,17 +1327,27 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
if (ofs->layers == NULL)
goto out;
- ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
- GFP_KERNEL);
- if (ofs->lower_fs == NULL)
+ ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL);
+ if (ofs->fs == NULL)
goto out;
- /* idx 0 is reserved for upper fs even with lower only overlay */
+ /* idx/fsid 0 are reserved for upper fs even with lower only overlay */
+ ofs->numfs++;
+
ofs->layers[0].mnt = ofs->upper_mnt;
ofs->layers[0].idx = 0;
ofs->layers[0].fsid = 0;
ofs->numlayer = 1;
+ /*
+ * All lower layers that share the same fs as upper layer, use the real
+ * upper st_dev.
+ */
+ if (ofs->upper_mnt) {
+ ofs->fs[0].sb = ofs->upper_mnt->mnt_sb;
+ ofs->fs[0].pseudo_dev = ofs->upper_mnt->mnt_sb->s_dev;
+ }
+
for (i = 0; i < numlower; i++) {
struct vfsmount *mnt;
struct inode *trap;
@@ -1379,10 +1385,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
ofs->layers[ofs->numlayer].mnt = mnt;
ofs->layers[ofs->numlayer].idx = ofs->numlayer;
ofs->layers[ofs->numlayer].fsid = fsid;
- if (fsid) {
- ofs->layers[ofs->numlayer].fs =
- &ofs->lower_fs[fsid - 1];
- }
+ ofs->layers[ofs->numlayer].fs = &ofs->fs[fsid];
ofs->numlayer++;
}
@@ -1394,18 +1397,18 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
* bits reserved for fsid, it emits a warning and uses the original
* inode number.
*/
- if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
+ if (ofs->numfs - !ofs->upper_mnt == 1) {
if (ofs->config.xino == OVL_XINO_ON)
pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
ofs->xino_mode = 0;
} else if (ofs->config.xino == OVL_XINO_ON && ofs->xino_mode < 0) {
/*
- * This is a roundup of number of bits needed for numlowerfs+1
- * (i.e. ilog2(numlowerfs+1 - 1) + 1). fsid 0 is reserved for
- * upper fs even with non upper overlay.
+ * This is a roundup of number of bits needed for encoding
+ * fsid, where fsid 0 is reserved for upper fs even with
+ * lower only overlay.
*/
BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31);
- ofs->xino_mode = ilog2(ofs->numlowerfs) + 1;
+ ofs->xino_mode = ilog2(ofs->numfs - 1) + 1;
}
if (ofs->xino_mode > 0) {