Messages in this thread Patch in this message | | | From | Marcos Paulo de Souza <> | Subject | [kernel PATCH 1/1] btrfs: Introduce new BTRFS_IOC_SNAP_DESTROY_V2 ioctl | Date | Mon, 20 Jan 2020 18:14:51 -0300 |
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From: Marcos Paulo de Souza <mpdesouza@suse.com>
This ioctl will be responsible for deleting a subvolume using it's id. This can be used when a system has a file system mounted from a subvolume, rather than the root file system, like below:
/ |- @subvol1 |- @subvol2 \- @subvol_default If only @subvol_default is mounted, we have no path to reach @subvol1 and @subvol2, thus no way to delete them. This patch introduces a new flag to allow BTRFS_IOC_SNAP_DESTORY_V2 to delete subvolume using subvolid.
Also in this patch, add BTRFS_SUBVOL_DELETE_BY_ID flag and add subvolid as a union member of fd in struct btrfs_ioctl_vol_args_v2.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> --- fs/btrfs/ctree.h | 8 ++++ fs/btrfs/export.c | 4 +- fs/btrfs/ioctl.c | 94 +++++++++++++++++++++++++++++++------- fs/btrfs/super.c | 2 +- include/uapi/linux/btrfs.h | 12 ++++- 5 files changed, 98 insertions(+), 22 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 569931dd0ce5..421a2f57f9ec 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -3010,6 +3010,8 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans, int btrfs_parse_options(struct btrfs_fs_info *info, char *options, unsigned long new_flags); int btrfs_sync_fs(struct super_block *sb, int wait); +char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, + u64 subvol_objectid); static inline __printf(2, 3) __cold void btrfs_no_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...) @@ -3442,6 +3444,12 @@ int btrfs_reada_wait(void *handle); void btrfs_reada_detach(void *handle); int btree_readahead_hook(struct extent_buffer *eb, int err); +/* export.c */ +struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, + u64 root_objectid, u32 generation, + int check_generation); +struct dentry *btrfs_get_parent(struct dentry *child); + static inline int is_fstree(u64 rootid) { if (rootid == BTRFS_FS_TREE_OBJECTID || diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c index 72e312cae69d..027411cdbae7 100644 --- a/fs/btrfs/export.c +++ b/fs/btrfs/export.c @@ -57,7 +57,7 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, return type; } -static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, +struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, u64 root_objectid, u32 generation, int check_generation) { @@ -152,7 +152,7 @@ static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); } -static struct dentry *btrfs_get_parent(struct dentry *child) +struct dentry *btrfs_get_parent(struct dentry *child) { struct inode *dir = d_inode(child); struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 0fa1c386d020..a03ff335a250 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2836,7 +2836,8 @@ static int btrfs_ioctl_get_subvol_rootref(struct file *file, void __user *argp) } static noinline int btrfs_ioctl_snap_destroy(struct file *file, - void __user *arg) + void __user *arg, + bool destroy_v2) { struct dentry *parent = file->f_path.dentry; struct btrfs_fs_info *fs_info = btrfs_sb(parent->d_sb); @@ -2845,34 +2846,85 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file, struct inode *inode; struct btrfs_root *root = BTRFS_I(dir)->root; struct btrfs_root *dest = NULL; - struct btrfs_ioctl_vol_args *vol_args; + struct btrfs_ioctl_vol_args *vol_args = NULL; + struct btrfs_ioctl_vol_args_v2 *vol_args2 = NULL; + char *name, *name_ptr = NULL; int namelen; int err = 0; - if (!S_ISDIR(dir->i_mode)) - return -ENOTDIR; + if (destroy_v2) { + vol_args2 = memdup_user(arg, sizeof(*vol_args2)); + if (IS_ERR(vol_args2)) + return PTR_ERR(vol_args2); - vol_args = memdup_user(arg, sizeof(*vol_args)); - if (IS_ERR(vol_args)) - return PTR_ERR(vol_args); + if (vol_args2->subvolid == 0) { + err = -EINVAL; + goto out; + } - vol_args->name[BTRFS_PATH_NAME_MAX] = '\0'; - namelen = strlen(vol_args->name); - if (strchr(vol_args->name, '/') || - strncmp(vol_args->name, "..", namelen) == 0) { - err = -EINVAL; - goto out; + if (!(vol_args2->flags & BTRFS_SUBVOL_DELETE_BY_ID)) { + err = -EINVAL; + goto out; + } + + dentry = btrfs_get_dentry(fs_info->sb, BTRFS_FIRST_FREE_OBJECTID, + vol_args2->subvolid, 0, 0); + if (IS_ERR(dentry)) { + err = PTR_ERR(dentry); + goto out; + } + + /* change the default parent since the subvolume being deleted + * can be outside of the current mount point + */ + parent = btrfs_get_parent(dentry); + + /* the only use of dentry was to get the parent, so we can + * release it now. Later on the dentry will be queried again to + * make sure the dentry will reside in the dentry cache + */ + dput(dentry); + if (IS_ERR(parent)) { + err = PTR_ERR(parent); + goto out; + } + dir = d_inode(parent); + + name_ptr = get_subvol_name_from_objectid(fs_info, vol_args2->subvolid); + if (IS_ERR(name_ptr)) { + err = PTR_ERR(name_ptr); + goto free_parent; + } + name = (char *)kbasename(name_ptr); + namelen = strlen(name); + } else { + vol_args = memdup_user(arg, sizeof(*vol_args)); + if (IS_ERR(vol_args)) + return PTR_ERR(vol_args); + + vol_args->name[BTRFS_PATH_NAME_MAX] = '\0'; + namelen = strlen(vol_args->name); + if (strchr(vol_args->name, '/') || + strncmp(vol_args->name, "..", namelen) == 0) { + err = -EINVAL; + goto out; + } + name = vol_args->name; + } + + if (!S_ISDIR(dir->i_mode)) { + err = -ENOTDIR; + goto free_subvol_name; } err = mnt_want_write_file(file); if (err) - goto out; - + goto free_subvol_name; err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT); if (err == -EINTR) goto out_drop_write; - dentry = lookup_one_len(vol_args->name, parent, namelen); + dentry = lookup_one_len(name, parent, namelen); if (IS_ERR(dentry)) { err = PTR_ERR(dentry); goto out_unlock_dir; @@ -2943,7 +2995,13 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file, inode_unlock(dir); out_drop_write: mnt_drop_write_file(file); +free_subvol_name: + kfree(name_ptr); +free_parent: + if (destroy_v2) + dput(parent); out: + kfree(vol_args2); kfree(vol_args); return err; } @@ -5452,7 +5510,9 @@ long btrfs_ioctl(struct file *file, unsigned int case BTRFS_IOC_SUBVOL_CREATE_V2: return btrfs_ioctl_snap_create_v2(file, argp, 1); case BTRFS_IOC_SNAP_DESTROY: - return btrfs_ioctl_snap_destroy(file, argp); + return btrfs_ioctl_snap_destroy(file, argp, false); + case BTRFS_IOC_SNAP_DESTROY_V2: + return btrfs_ioctl_snap_destroy(file, argp, true); case BTRFS_IOC_SUBVOL_GETFLAGS: return btrfs_ioctl_subvol_getflags(file, argp); case BTRFS_IOC_SUBVOL_SETFLAGS: diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index a906315efd19..a448d2bb93e6 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1024,7 +1024,7 @@ static int btrfs_parse_subvol_options(const char *options, char **subvol_name, return error; } -static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, +char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, u64 subvol_objectid) { struct btrfs_root *root = fs_info->tree_root; diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index 7a8bc8b920f5..1be03082e49a 100644 --- a/include/uapi/linux/btrfs.h +++ b/include/uapi/linux/btrfs.h @@ -42,11 +42,14 @@ struct btrfs_ioctl_vol_args { #define BTRFS_DEVICE_SPEC_BY_ID (1ULL << 3) +#define BTRFS_SUBVOL_DELETE_BY_ID (1ULL << 4) + #define BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED \ (BTRFS_SUBVOL_CREATE_ASYNC | \ BTRFS_SUBVOL_RDONLY | \ BTRFS_SUBVOL_QGROUP_INHERIT | \ - BTRFS_DEVICE_SPEC_BY_ID) + BTRFS_DEVICE_SPEC_BY_ID | \ + BTRFS_SUBVOL_DELETE_BY_ID) #define BTRFS_FSID_SIZE 16 #define BTRFS_UUID_SIZE 16 @@ -108,7 +111,10 @@ struct btrfs_ioctl_qgroup_limit_args { */ struct btrfs_ioctl_vol_args_v2 { - __s64 fd; + union { + __s64 fd; + __u64 subvolid; + }; __u64 transid; __u64 flags; union { @@ -949,5 +955,7 @@ enum btrfs_err_code { struct btrfs_ioctl_get_subvol_rootref_args) #define BTRFS_IOC_INO_LOOKUP_USER _IOWR(BTRFS_IOCTL_MAGIC, 62, \ struct btrfs_ioctl_ino_lookup_user_args) +#define BTRFS_IOC_SNAP_DESTROY_V2 _IOW(BTRFS_IOCTL_MAGIC, 63, \ + struct btrfs_ioctl_vol_args_v2) #endif /* _UAPI_LINUX_BTRFS_H */ -- 2.24.0
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