From: Goffredo Baroncelli <kreijack@xxxxxxxxx>
When more than one subvol= options are passed, btrfs try to mount
each subvolume until the first one succeed. Up to 5 subvol= options
can be passed.
Signed-off-by: Goffredo Baroncelli <kreijack@xxxxxxxxx>
---
fs/btrfs/super.c | 71 ++++++++++++++++++++++++++++++------------------
1 file changed, 45 insertions(+), 26 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index bc73fd670702..12d066e8d52c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -52,6 +52,8 @@
#define CREATE_TRACE_POINTS
#include <trace/events/btrfs.h>
+#define SUBVOL_NAMES_COUNT 5
+
static const struct super_operations btrfs_super_ops;
/*
@@ -974,12 +976,13 @@ static int btrfs_parse_device_options(const char *options, fmode_t flags,
*
* The value is later passed to mount_subvol()
*/
-static int btrfs_parse_subvol_options(const char *options, char **subvol_name,
- u64 *subvol_objectid)
+static int btrfs_parse_subvol_options(const char *options, char **subvol_names,
+ u64 *subvol_objectid)
{
substring_t args[MAX_OPT_ARGS];
char *opts, *orig, *p;
int error = 0;
+ int svi = 0;
u64 subvolid;
if (!options)
@@ -1002,12 +1005,17 @@ static int btrfs_parse_subvol_options(const char *options, char **subvol_name,
token = match_token(p, tokens, args);
switch (token) {
case Opt_subvol:
- kfree(*subvol_name);
- *subvol_name = match_strdup(&args[0]);
- if (!*subvol_name) {
+ if (svi >= SUBVOL_NAMES_COUNT) {
+ pr_err("BTRFS: too much 'subvol=' mount options\n");
+ error = -E2BIG;
+ goto out;
+ }
+ subvol_names[svi] = match_strdup(&args[0]);
+ if (!subvol_names[svi]) {
error = -ENOMEM;
goto out;
}
+ svi++;
break;
case Opt_subvolid:
error = match_u64(&args[0], &subvolid);
@@ -1429,13 +1437,16 @@ static inline int is_subvolume_inode(struct inode *inode)
return 0;
}
-static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
+static struct dentry *mount_subvol(char **subvol_names,
+ u64 subvol_objectid,
struct vfsmount *mnt)
{
struct dentry *root;
int ret;
+ const char *sv;
+ int i;
- if (!subvol_name) {
+ if (!subvol_names[0]) {
if (!subvol_objectid) {
ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
&subvol_objectid);
@@ -1444,17 +1455,27 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
goto out;
}
}
- subvol_name = btrfs_get_subvol_name_from_objectid(
+ subvol_names[0] = btrfs_get_subvol_name_from_objectid(
btrfs_sb(mnt->mnt_sb), subvol_objectid);
- if (IS_ERR(subvol_name)) {
- root = ERR_CAST(subvol_name);
- subvol_name = NULL;
+ if (IS_ERR(subvol_names[0])) {
+ root = ERR_CAST(subvol_names[0]);
+ subvol_names[0] = NULL;
goto out;
}
}
- root = mount_subtree(mnt, subvol_name);
+ for (i = 0 ; i < SUBVOL_NAMES_COUNT ; i++) {
+ if (!subvol_names[i])
+ break;
+
+ root = mount_subtree(mnt, subvol_names[i]);
+ if (!IS_ERR(root)) {
+ sv = subvol_names[i];
+ break;
+ }
+ }
+
/* mount_subtree() drops our reference on the vfsmount. */
mnt = NULL;
@@ -1466,8 +1487,7 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
ret = 0;
if (!is_subvolume_inode(root_inode)) {
- btrfs_err(fs_info, "'%s' is not a valid subvolume",
- subvol_name);
+ btrfs_err(fs_info, "'%s' is not a valid subvolume", sv);
ret = -EINVAL;
}
if (subvol_objectid && root_objectid != subvol_objectid) {
@@ -1478,7 +1498,7 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
*/
btrfs_err(fs_info,
"subvol '%s' does not match subvolid %llu",
- subvol_name, subvol_objectid);
+ sv, subvol_objectid);
ret = -EINVAL;
}
if (ret) {
@@ -1490,7 +1510,6 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
out:
mntput(mnt);
- kfree(subvol_name);
return root;
}
@@ -1636,15 +1655,16 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
{
struct vfsmount *mnt_root;
struct dentry *root;
- char *subvol_name = NULL;
+ int i;
+ char *subvol_names[SUBVOL_NAMES_COUNT] = {0,};
u64 subvol_objectid = 0;
int error = 0;
- error = btrfs_parse_subvol_options(data, &subvol_name,
- &subvol_objectid);
+ error = btrfs_parse_subvol_options(data, subvol_names,
+ &subvol_objectid);
if (error) {
- kfree(subvol_name);
- return ERR_PTR(error);
+ root = ERR_PTR(error);
+ goto out;
}
/* mount device's root (/) */
@@ -1658,7 +1678,6 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
flags | SB_RDONLY, device_name, data);
if (IS_ERR(mnt_root)) {
root = ERR_CAST(mnt_root);
- kfree(subvol_name);
goto out;
}
@@ -1668,21 +1687,21 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
if (error < 0) {
root = ERR_PTR(error);
mntput(mnt_root);
- kfree(subvol_name);
goto out;
}
}
}
if (IS_ERR(mnt_root)) {
root = ERR_CAST(mnt_root);
- kfree(subvol_name);
goto out;
}
- /* mount_subvol() will free subvol_name and mnt_root */
- root = mount_subvol(subvol_name, subvol_objectid, mnt_root);
+ /* mount_subvol() will free mnt_root */
+ root = mount_subvol(subvol_names, subvol_objectid, mnt_root);
out:
+ for (i = 0 ; i < SUBVOL_NAMES_COUNT ; i++)
+ kfree(subvol_names[i]);
return root;
}
--
2.28.0.rc1
