From 1ddb4eb804cbff5384a8f5f95276e81d3e9c34ce Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Mon, 6 Apr 2015 10:57:17 +0200 Subject: [PATCH] btrfs: support recursively removing btrfs snapshots --- src/shared/audit.h | 1 - src/shared/btrfs-ctree.h | 6 ++ src/shared/btrfs-util.c | 163 +++++++++++++++++++++++++++++++------ src/shared/btrfs-util.h | 4 +- src/shared/machine-image.c | 2 +- src/shared/missing.h | 8 ++ src/shared/rm-rf.c | 44 +++++++++- 7 files changed, 196 insertions(+), 32 deletions(-) diff --git a/src/shared/audit.h b/src/shared/audit.h index 781866ae1..3df9cc627 100644 --- a/src/shared/audit.h +++ b/src/shared/audit.h @@ -25,7 +25,6 @@ #include #include - int audit_session_from_pid(pid_t pid, uint32_t *id); int audit_loginuid_from_pid(pid_t pid, uid_t *uid); diff --git a/src/shared/btrfs-ctree.h b/src/shared/btrfs-ctree.h index 8b6f1ab4f..d3ae57331 100644 --- a/src/shared/btrfs-ctree.h +++ b/src/shared/btrfs-ctree.h @@ -90,3 +90,9 @@ struct btrfs_qgroup_limit_item { le64_t rsv_rfer; le64_t rsv_excl; } _packed_; + +struct btrfs_root_ref { + le64_t dirid; + le64_t sequence; + le16_t name_len; +} _packed_; diff --git a/src/shared/btrfs-util.c b/src/shared/btrfs-util.c index a95cb8394..fc795cb18 100644 --- a/src/shared/btrfs-util.c +++ b/src/shared/btrfs-util.c @@ -124,14 +124,14 @@ int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, bool read_only, b r = copy_directory_fd(old_fd, new_path, true); if (r < 0) { - btrfs_subvol_remove(new_path); + btrfs_subvol_remove(new_path, false); return r; } if (read_only) { r = btrfs_subvol_set_read_only(new_path, true); if (r < 0) { - btrfs_subvol_remove(new_path); + btrfs_subvol_remove(new_path, false); return r; } } @@ -211,30 +211,6 @@ int btrfs_subvol_make_label(const char *path) { return mac_smack_fix(path, false, false); } -int btrfs_subvol_remove(const char *path) { - struct btrfs_ioctl_vol_args args = {}; - _cleanup_close_ int fd = -1; - const char *subvolume; - int r; - - assert(path); - - r = extract_subvolume_name(path, &subvolume); - if (r < 0) - return r; - - fd = open_parent(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); - if (fd < 0) - return fd; - - strncpy(args.name, subvolume, sizeof(args.name)-1); - - if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &args) < 0) - return -errno; - - return 0; -} - int btrfs_subvol_set_read_only_fd(int fd, bool b) { uint64_t flags, nflags; struct stat st; @@ -798,3 +774,138 @@ int btrfs_resize_loopback(const char *p, uint64_t new_size, bool grow_only) { return btrfs_resize_loopback_fd(fd, new_size, grow_only); } + +static int subvol_remove_children(int fd, const char *subvolume, uint64_t subvol_id, bool recursive) { + struct btrfs_ioctl_search_args args = { + .key.tree_id = BTRFS_ROOT_TREE_OBJECTID, + + .key.min_objectid = BTRFS_FIRST_FREE_OBJECTID, + .key.max_objectid = BTRFS_LAST_FREE_OBJECTID, + + .key.min_type = BTRFS_ROOT_BACKREF_KEY, + .key.max_type = BTRFS_ROOT_BACKREF_KEY, + + .key.min_transid = 0, + .key.max_transid = (uint64_t) -1, + }; + + struct btrfs_ioctl_vol_args vol_args = {}; + _cleanup_close_ int subvol_fd = -1; + int r; + + assert(fd >= 0); + assert(subvolume); + + /* First, try to remove the subvolume. If it happens to be + * already empty, this will just work. */ + strncpy(vol_args.name, subvolume, sizeof(vol_args.name)-1); + if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &vol_args) >= 0) + return 0; + if (!recursive || errno != ENOTEMPTY) + return -errno; + + /* OK, the subvolume is not empty, let's look for child + * subvolumes, and remove them, first */ + subvol_fd = openat(fd, subvolume, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (subvol_fd < 0) + return -errno; + + if (subvol_id == 0) { + r = btrfs_subvol_get_id_fd(subvol_fd, &subvol_id); + if (r < 0) + return r; + } + + args.key.min_offset = args.key.max_offset = subvol_id; + + while (btrfs_ioctl_search_args_compare(&args) <= 0) { + const struct btrfs_ioctl_search_header *sh; + unsigned i; + + args.key.nr_items = 256; + if (ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args) < 0) + return -errno; + + if (args.key.nr_items <= 0) + break; + + FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) { + _cleanup_free_ char *p = NULL; + const struct btrfs_root_ref *ref; + struct btrfs_ioctl_ino_lookup_args ino_args; + + btrfs_ioctl_search_args_set(&args, sh); + + if (sh->type != BTRFS_ROOT_BACKREF_KEY) + continue; + if (sh->offset != subvol_id) + continue; + + ref = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh); + + p = strndup((char*) ref + sizeof(struct btrfs_root_ref), le64toh(ref->name_len)); + if (!p) + return -ENOMEM; + + zero(ino_args); + ino_args.treeid = subvol_id; + ino_args.objectid = ref->dirid; + + if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0) + return -errno; + + if (isempty(ino_args.name)) + /* Subvolume is in the top-level + * directory of the subvolume. */ + r = subvol_remove_children(subvol_fd, p, sh->objectid, recursive); + else { + _cleanup_close_ int child_fd = -1; + + /* Subvolume is somewhere further down, + * hence we need to open the + * containing directory first */ + + child_fd = openat(subvol_fd, ino_args.name, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (child_fd < 0) + return -errno; + + r = subvol_remove_children(child_fd, p, sh->objectid, recursive); + } + if (r < 0) + return r; + } + + /* Increase search key by one, to read the next item, if we can. */ + if (!btrfs_ioctl_search_args_inc(&args)) + break; + } + + /* OK, the child subvolumes should all be gone now, let's try + * again to remove the subvolume */ + if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &vol_args) < 0) + return -errno; + + return 0; +} + +int btrfs_subvol_remove(const char *path, bool recursive) { + _cleanup_close_ int fd = -1; + const char *subvolume; + int r; + + assert(path); + + r = extract_subvolume_name(path, &subvolume); + if (r < 0) + return r; + + fd = open_parent(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (fd < 0) + return fd; + + return subvol_remove_children(fd, subvolume, 0, recursive); +} + +int btrfs_subvol_remove_fd(int fd, const char *subvolume, bool recursive) { + return subvol_remove_children(fd, subvolume, 0, recursive); +} diff --git a/src/shared/btrfs-util.h b/src/shared/btrfs-util.h index 968572343..06ecc11b4 100644 --- a/src/shared/btrfs-util.h +++ b/src/shared/btrfs-util.h @@ -47,7 +47,6 @@ int btrfs_is_snapshot(int fd); int btrfs_subvol_make(const char *path); int btrfs_subvol_make_label(const char *path); -int btrfs_subvol_remove(const char *path); int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, bool read_only, bool fallback_copy); int btrfs_subvol_snapshot(const char *old_path, const char *new_path, bool read_only, bool fallback_copy); @@ -76,3 +75,6 @@ int btrfs_quota_limit(const char *path, uint64_t referenced_max); int btrfs_resize_loopback_fd(int fd, uint64_t size, bool grow_only); int btrfs_resize_loopback(const char *path, uint64_t size, bool grow_only); + +int btrfs_subvol_remove(const char *path, bool recursive); +int btrfs_subvol_remove_fd(int fd, const char *subvolume, bool recursive); diff --git a/src/shared/machine-image.c b/src/shared/machine-image.c index f166e9410..fb72123f1 100644 --- a/src/shared/machine-image.c +++ b/src/shared/machine-image.c @@ -358,7 +358,7 @@ int image_remove(Image *i) { switch (i->type) { case IMAGE_SUBVOLUME: - return btrfs_subvol_remove(i->path); + return btrfs_subvol_remove(i->path, true); case IMAGE_DIRECTORY: /* Allow deletion of read-only directories */ diff --git a/src/shared/missing.h b/src/shared/missing.h index eddfa78b8..c51f373b6 100644 --- a/src/shared/missing.h +++ b/src/shared/missing.h @@ -424,6 +424,10 @@ struct btrfs_ioctl_clone_range_args { #define BTRFS_FIRST_FREE_OBJECTID 256 #endif +#ifndef BTRFS_LAST_FREE_OBJECTID +#define BTRFS_LAST_FREE_OBJECTID -256ULL +#endif + #ifndef BTRFS_ROOT_TREE_OBJECTID #define BTRFS_ROOT_TREE_OBJECTID 1 #endif @@ -448,6 +452,10 @@ struct btrfs_ioctl_clone_range_args { #define BTRFS_QGROUP_LIMIT_KEY 244 #endif +#ifndef BTRFS_ROOT_BACKREF_KEY +#define BTRFS_ROOT_BACKREF_KEY 144 +#endif + #ifndef BTRFS_SUPER_MAGIC #define BTRFS_SUPER_MAGIC 0x9123683E #endif diff --git a/src/shared/rm-rf.c b/src/shared/rm-rf.c index eeb2e3919..a89e8afc2 100644 --- a/src/shared/rm-rf.c +++ b/src/shared/rm-rf.c @@ -21,6 +21,7 @@ #include "util.h" #include "path-util.h" +#include "btrfs-util.h" #include "rm-rf.h" int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) { @@ -75,7 +76,8 @@ int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) { if (streq(de->d_name, ".") || streq(de->d_name, "..")) continue; - if (de->d_type == DT_UNKNOWN || (de->d_type == DT_DIR && root_dev)) { + if (de->d_type == DT_UNKNOWN || + (de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) { if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) { if (ret == 0 && errno != ENOENT) ret = -errno; @@ -114,6 +116,30 @@ int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) { continue; } + if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) { + + /* This could be a subvolume, try to remove it */ + + r = btrfs_subvol_remove_fd(fd, de->d_name, true); + if (r < 0) { + if (r != -ENOTTY && r != -EINVAL) { + if (ret == 0) + ret = r; + + safe_close(subdir_fd); + continue; + } + + /* ENOTTY, then it wasn't a + * btrfs subvolume, continue + * below. */ + } else { + /* It was a subvolume, continue. */ + safe_close(subdir_fd); + continue; + } + } + /* We pass REMOVE_PHYSICAL here, to avoid * doing the fstatfs() to check the file * system type again for each directory */ @@ -150,6 +176,18 @@ int rm_rf(const char *path, RemoveFlags flags) { return -EPERM; } + if ((flags & (REMOVE_SUBVOLUME|REMOVE_ROOT|REMOVE_PHYSICAL)) == (REMOVE_SUBVOLUME|REMOVE_ROOT|REMOVE_PHYSICAL)) { + /* Try to remove as subvolume first */ + r = btrfs_subvol_remove(path, true); + if (r >= 0) + return r; + + if (r != -ENOTTY && r != -EINVAL) + return r; + + /* Not btrfs or not a subvolume */ + } + fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME); if (fd < 0) { @@ -176,8 +214,8 @@ int rm_rf(const char *path, RemoveFlags flags) { r = rm_rf_children(fd, flags, NULL); if (flags & REMOVE_ROOT) { - if (rmdir(path) < 0 && errno != ENOENT) { - if (r == 0) + if (rmdir(path) < 0) { + if (r == 0 && errno != ENOENT) r = -errno; } } -- 2.30.2