This patch is already accepted in upstream btrfs-unstable git tree as commit e15d0542426f063dc53b4c51bdfc11e0bbe4d298. Below is a backport to mrst 2.6.37 kernel.
We create two subvolumes (meego_root and meego_home) in btrfs root directory. And set meego_root as default mount subvolume. After we remount btrfs, meego_root is mounted to top directory by default. Then when we try to mount meego_home (subvol=meego_home) to a subdirectory, it failed. The problem is when default mount subvolume is set to meego_root, we search meego_home in meego_root but can not find it. So the solution is to add a new mount option (subvolrootid) to specify subvol id of root and search subvol name in it. For our case, now we can use "-o subvolrootid=0,subvol=meego_home) to mount meego_home. Detail information can be found in meego bugzilla: https://bugs.meego.com/show_bug.cgi?id=15055 Signed-off-by: Zhong, Xin <[email protected]> --- fs/btrfs/super.c | 42 +++++++++++++++++++++++++++++++++--------- 1 files changed, 33 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 883c6fa..738e27a 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -71,7 +71,7 @@ enum { Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress, Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard, Opt_space_cache, Opt_clear_cache, Opt_err, - Opt_user_subvol_rm_allowed, + Opt_user_subvol_rm_allowed, Opt_subvolrootid }; static match_table_t tokens = { @@ -98,6 +98,7 @@ static match_table_t tokens = { {Opt_space_cache, "space_cache"}, {Opt_clear_cache, "clear_cache"}, {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"}, + {Opt_subvolrootid, "subvolrootid=%d"}, {Opt_err, NULL}, }; @@ -139,6 +140,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options) break; case Opt_subvol: case Opt_subvolid: + case Opt_subvolrootid: case Opt_device: /* * These are parsed by btrfs_parse_early_options @@ -274,7 +276,7 @@ out: */ static int btrfs_parse_early_options(const char *options, fmode_t flags, void *holder, char **subvol_name, u64 *subvol_objectid, - struct btrfs_fs_devices **fs_devices) + u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices) { substring_t args[MAX_OPT_ARGS]; char *opts, *p; @@ -314,6 +316,18 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags, *subvol_objectid = intarg; } break; + case Opt_subvolrootid: + intarg = 0; + error = match_int(&args[0], &intarg); + if (!error) { + /* we want the original fs_tree */ + if (!intarg) + *subvol_rootid = + BTRFS_FS_TREE_OBJECTID; + else + *subvol_rootid = intarg; + } + break; case Opt_device: error = btrfs_scan_one_device(match_strdup(&args[0]), flags, holder, fs_devices); @@ -601,6 +615,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, fmode_t mode = FMODE_READ; char *subvol_name = NULL; u64 subvol_objectid = 0; + u64 subvol_rootid = 0; int error = 0; if (!(flags & MS_RDONLY)) @@ -608,7 +623,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, error = btrfs_parse_early_options(data, mode, fs_type, &subvol_name, &subvol_objectid, - &fs_devices); + &subvol_rootid, &fs_devices); if (error) return ERR_PTR(error); @@ -670,15 +685,17 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, s->s_flags |= MS_ACTIVE; } - root = get_default_root(s, subvol_objectid); - if (IS_ERR(root)) { - error = PTR_ERR(root); - deactivate_locked_super(s); - goto error_free_subvol_name; - } /* if they gave us a subvolume name bind mount into that */ if (strcmp(subvol_name, ".")) { struct dentry *new_root; + + root = get_default_root(s, subvol_rootid); + if (IS_ERR(root)) { + error = PTR_ERR(root); + deactivate_locked_super(s); + goto error_free_subvol_name; + } + mutex_lock(&root->d_inode->i_mutex); new_root = lookup_one_len(subvol_name, root, strlen(subvol_name)); @@ -699,6 +716,13 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, } dput(root); root = new_root; + } else { + root = get_default_root(s, subvol_objectid); + if (IS_ERR(root)) { + error = PTR_ERR(root); + deactivate_locked_super(s); + goto error_free_subvol_name; + } } kfree(subvol_name); -- 1.7.0.4 _______________________________________________ MeeGo-kernel mailing list [email protected] http://lists.meego.com/listinfo/meego-kernel
