X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fshared%2Fbtrfs-util.c;h=49528dbf0152e119d6ee1d9f3ed7acaa0f067b41;hp=164ac9f337c8522c5ec393cd9f82ec7573918140;hb=d2febf7f92eba0919773ce93d80df50fd3faeb5d;hpb=b6b1849830f5e4a6065c3b0c993668e500c954d3 diff --git a/src/shared/btrfs-util.c b/src/shared/btrfs-util.c index 164ac9f33..49528dbf0 100644 --- a/src/shared/btrfs-util.c +++ b/src/shared/btrfs-util.c @@ -31,13 +31,21 @@ #include "util.h" #include "path-util.h" #include "macro.h" -#include "strv.h" #include "copy.h" #include "selinux-util.h" #include "smack-util.h" +#include "fileio.h" #include "btrfs-ctree.h" #include "btrfs-util.h" +/* WARNING: Be careful with file system ioctls! When we get an fd, we + * need to make sure it either refers to only a regular file or + * directory, or that it is located on btrfs, before invoking any + * btrfs ioctls. The ioctl numbers are reused by some device drivers + * (such as DRM), and hence might have bad effects when invoked on + * device nodes (that reference drivers) rather than fds to normal + * files or directories. */ + static int validate_subvolume_name(const char *name) { if (!filename_is_valid(name)) @@ -83,17 +91,10 @@ static int extract_subvolume_name(const char *path, const char **subvolume) { return 0; } -int btrfs_is_snapshot(int fd) { - struct stat st; +int btrfs_is_filesystem(int fd) { struct statfs sfs; - /* On btrfs subvolumes always have the inode 256 */ - - if (fstat(fd, &st) < 0) - return -errno; - - if (!S_ISDIR(st.st_mode) || st.st_ino != 256) - return 0; + assert(fd >= 0); if (fstatfs(fd, &sfs) < 0) return -errno; @@ -101,65 +102,20 @@ int btrfs_is_snapshot(int fd) { return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC); } -int btrfs_subvol_snapshot(const char *old_path, const char *new_path, bool read_only, bool fallback_copy) { - struct btrfs_ioctl_vol_args_v2 args = { - .flags = read_only ? BTRFS_SUBVOL_RDONLY : 0, - }; - _cleanup_close_ int old_fd = -1, new_fd = -1; - const char *subvolume; - int r; - - assert(old_path); - - old_fd = open(old_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); - if (old_fd < 0) - return -errno; - - r = btrfs_is_snapshot(old_fd); - if (r < 0) - return r; - if (r == 0) { - - if (fallback_copy) { - r = btrfs_subvol_make(new_path); - if (r < 0) - return r; - - r = copy_directory_fd(old_fd, new_path, true); - if (r < 0) { - btrfs_subvol_remove(new_path); - return r; - } - - if (read_only) { - r = btrfs_subvol_set_read_only(new_path, true); - if (r < 0) { - btrfs_subvol_remove(new_path); - return r; - } - } - - return 0; - } - - return -EISDIR; - } - - r = extract_subvolume_name(new_path, &subvolume); - if (r < 0) - return r; +int btrfs_is_subvol(int fd) { + struct stat st; - new_fd = open_parent(new_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); - if (new_fd < 0) - return new_fd; + assert(fd >= 0); - strncpy(args.name, subvolume, sizeof(args.name)-1); - args.fd = old_fd; + /* On btrfs subvolumes always have the inode 256 */ - if (ioctl(new_fd, BTRFS_IOC_SNAP_CREATE_V2, &args) < 0) + if (fstat(fd, &st) < 0) return -errno; - return 0; + if (!S_ISDIR(st.st_mode) || st.st_ino != 256) + return 0; + + return btrfs_is_filesystem(fd); } int btrfs_subvol_make(const char *path) { @@ -204,37 +160,17 @@ 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; +int btrfs_subvol_set_read_only_fd(int fd, bool b) { + uint64_t flags, nflags; + struct stat st; - strncpy(args.name, subvolume, sizeof(args.name)-1); + assert(fd >= 0); - if (ioctl(fd, BTRFS_IOC_SNAP_DESTROY, &args) < 0) + if (fstat(fd, &st) < 0) return -errno; - return 0; -} - -int btrfs_subvol_set_read_only(const char *path, bool b) { - _cleanup_close_ int fd = -1; - uint64_t flags, nflags; - - fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC); - if (fd < 0) - return -errno; + if (!S_ISDIR(st.st_mode) || st.st_ino != 256) + return -EINVAL; if (ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags) < 0) return -errno; @@ -253,8 +189,27 @@ int btrfs_subvol_set_read_only(const char *path, bool b) { return 0; } +int btrfs_subvol_set_read_only(const char *path, bool b) { + _cleanup_close_ int fd = -1; + + fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (fd < 0) + return -errno; + + return btrfs_subvol_set_read_only_fd(fd, b); +} + int btrfs_subvol_get_read_only_fd(int fd) { uint64_t flags; + struct stat st; + + assert(fd >= 0); + + if (fstat(fd, &st) < 0) + return -errno; + + if (!S_ISDIR(st.st_mode) || st.st_ino != 256) + return -EINVAL; if (ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags) < 0) return -errno; @@ -263,11 +218,21 @@ int btrfs_subvol_get_read_only_fd(int fd) { } int btrfs_reflink(int infd, int outfd) { + struct stat st; int r; assert(infd >= 0); assert(outfd >= 0); + /* Make sure we invoke the ioctl on a regular file, so that no + * device driver accidentally gets it. */ + + if (fstat(outfd, &st) < 0) + return -errno; + + if (!S_ISREG(st.st_mode)) + return -EINVAL; + r = ioctl(outfd, BTRFS_IOC_CLONE, infd); if (r < 0) return -errno; @@ -275,17 +240,46 @@ int btrfs_reflink(int infd, int outfd) { return 0; } -int btrfs_get_block_device(const char *path, dev_t *dev) { +int btrfs_clone_range(int infd, uint64_t in_offset, int outfd, uint64_t out_offset, uint64_t sz) { + struct btrfs_ioctl_clone_range_args args = { + .src_fd = infd, + .src_offset = in_offset, + .src_length = sz, + .dest_offset = out_offset, + }; + struct stat st; + int r; + + assert(infd >= 0); + assert(outfd >= 0); + assert(sz > 0); + + if (fstat(outfd, &st) < 0) + return -errno; + + if (!S_ISREG(st.st_mode)) + return -EINVAL; + + r = ioctl(outfd, BTRFS_IOC_CLONE_RANGE, &args); + if (r < 0) + return -errno; + + return 0; +} + +int btrfs_get_block_device_fd(int fd, dev_t *dev) { struct btrfs_ioctl_fs_info_args fsi = {}; - _cleanup_close_ int fd = -1; uint64_t id; + int r; - assert(path); + assert(fd >= 0); assert(dev); - fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); - if (fd < 0) - return -errno; + r = btrfs_is_filesystem(fd); + if (r < 0) + return r; + if (!r) + return -ENOTTY; if (ioctl(fd, BTRFS_IOC_FS_INFO, &fsi) < 0) return -errno; @@ -323,14 +317,34 @@ int btrfs_get_block_device(const char *path, dev_t *dev) { return -ENODEV; } +int btrfs_get_block_device(const char *path, dev_t *dev) { + _cleanup_close_ int fd = -1; + + assert(path); + assert(dev); + + fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC); + if (fd < 0) + return -errno; + + return btrfs_get_block_device_fd(fd, dev); +} + int btrfs_subvol_get_id_fd(int fd, uint64_t *ret) { struct btrfs_ioctl_ino_lookup_args args = { .objectid = BTRFS_FIRST_FREE_OBJECTID }; + int r; assert(fd >= 0); assert(ret); + r = btrfs_is_filesystem(fd); + if (r < 0) + return r; + if (!r) + return -ENOTTY; + if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args) < 0) return -errno; @@ -338,6 +352,77 @@ int btrfs_subvol_get_id_fd(int fd, uint64_t *ret) { return 0; } +static bool btrfs_ioctl_search_args_inc(struct btrfs_ioctl_search_args *args) { + assert(args); + + /* the objectid, type, offset together make up the btrfs key, + * which is considered a single 136byte integer when + * comparing. This call increases the counter by one, dealing + * with the overflow between the overflows */ + + if (args->key.min_offset < (uint64_t) -1) { + args->key.min_offset++; + return true; + } + + if (args->key.min_type < (uint8_t) -1) { + args->key.min_type++; + args->key.min_offset = 0; + return true; + } + + if (args->key.min_objectid < (uint64_t) -1) { + args->key.min_objectid++; + args->key.min_offset = 0; + args->key.min_type = 0; + return true; + } + + return 0; +} + +static void btrfs_ioctl_search_args_set(struct btrfs_ioctl_search_args *args, const struct btrfs_ioctl_search_header *h) { + assert(args); + assert(h); + + args->key.min_objectid = h->objectid; + args->key.min_type = h->type; + args->key.min_offset = h->offset; +} + +static int btrfs_ioctl_search_args_compare(const struct btrfs_ioctl_search_args *args) { + assert(args); + + /* Compare min and max */ + + if (args->key.min_objectid < args->key.max_objectid) + return -1; + if (args->key.min_objectid > args->key.max_objectid) + return 1; + + if (args->key.min_type < args->key.max_type) + return -1; + if (args->key.min_type > args->key.max_type) + return 1; + + if (args->key.min_offset < args->key.max_offset) + return -1; + if (args->key.min_offset > args->key.max_offset) + return 1; + + return 0; +} + +#define FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) \ + for ((i) = 0, \ + (sh) = (const struct btrfs_ioctl_search_header*) (args).buf; \ + (i) < (args).key.nr_items; \ + (i)++, \ + (sh) = (const struct btrfs_ioctl_search_header*) ((uint8_t*) (sh) + sizeof(struct btrfs_ioctl_search_header) + (sh)->len)) + +#define BTRFS_IOCTL_SEARCH_HEADER_BODY(sh) \ + ((void*) ((uint8_t*) sh + sizeof(struct btrfs_ioctl_search_header))) + int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *ret) { struct btrfs_ioctl_search_args args = { /* Tree of tree roots */ @@ -347,9 +432,10 @@ int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *ret) { .key.min_type = BTRFS_ROOT_ITEM_KEY, .key.max_type = BTRFS_ROOT_ITEM_KEY, - /* No restrictions on the other components */ .key.min_offset = 0, .key.max_offset = (uint64_t) -1, + + /* No restrictions on the other components */ .key.min_transid = 0, .key.max_transid = (uint64_t) -1, }; @@ -367,7 +453,7 @@ int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *ret) { args.key.min_objectid = args.key.max_objectid = subvol_id; - for (;;) { + while (btrfs_ioctl_search_args_compare(&args) <= 0) { const struct btrfs_ioctl_search_header *sh; unsigned i; @@ -378,25 +464,23 @@ int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *ret) { if (args.key.nr_items <= 0) break; - for (i = 0, - sh = (const struct btrfs_ioctl_search_header*) args.buf; - i < args.key.nr_items; - i++, - args.key.min_type = sh->type, - args.key.min_offset = sh->offset, - args.key.min_objectid = sh->objectid, - sh = (const struct btrfs_ioctl_search_header*) ((uint8_t*) sh + sizeof(struct btrfs_ioctl_search_header) + sh->len)) { + FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) { const struct btrfs_root_item *ri; + /* Make sure we start the next search at least from this entry */ + btrfs_ioctl_search_args_set(&args, sh); + if (sh->objectid != subvol_id) continue; if (sh->type != BTRFS_ROOT_ITEM_KEY) continue; + + /* Older versions of the struct lacked the otime setting */ if (sh->len < offsetof(struct btrfs_root_item, otime) + sizeof(struct btrfs_timespec)) continue; - ri = (const struct btrfs_root_item *)(args.buf + sizeof(struct btrfs_ioctl_search_header)); + ri = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh); ret->otime = (usec_t) le64toh(ri->otime.sec) * USEC_PER_SEC + (usec_t) le32toh(ri->otime.nsec) / NSEC_PER_USEC; @@ -412,8 +496,8 @@ int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *ret) { goto finish; } - args.key.min_offset++; - if (!args.key.min_offset) /* overflow */ + /* Increase search key by one, to read the next item, if we can. */ + if (!btrfs_ioctl_search_args_inc(&args)) break; } @@ -430,13 +514,14 @@ int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *ret) { /* Tree of quota items */ .key.tree_id = BTRFS_QUOTA_TREE_OBJECTID, + /* The object ID is always 0 */ + .key.min_objectid = 0, + .key.max_objectid = 0, + /* Look precisely for the quota items */ .key.min_type = BTRFS_QGROUP_STATUS_KEY, .key.max_type = BTRFS_QGROUP_LIMIT_KEY, - .key.min_objectid = 0, - .key.max_objectid = 0, - /* No restrictions on the other components */ .key.min_transid = 0, .key.max_transid = (uint64_t) -1, @@ -455,7 +540,7 @@ int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *ret) { args.key.min_offset = args.key.max_offset = subvol_id; - for (;;) { + while (btrfs_ioctl_search_args_compare(&args) <= 0) { const struct btrfs_ioctl_search_header *sh; unsigned i; @@ -466,40 +551,32 @@ int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *ret) { if (args.key.nr_items <= 0) break; - for (i = 0, - sh = (const struct btrfs_ioctl_search_header*) args.buf; - i < args.key.nr_items; - i++, - args.key.min_type = sh->type, - args.key.min_offset = sh->offset, - args.key.min_objectid = sh->objectid, - sh = (const struct btrfs_ioctl_search_header*) ((uint8_t*) sh + sizeof(struct btrfs_ioctl_search_header) + sh->len)) { + FOREACH_BTRFS_IOCTL_SEARCH_HEADER(i, sh, args) { - const void *body; + /* Make sure we start the next search at least from this entry */ + btrfs_ioctl_search_args_set(&args, sh); if (sh->objectid != 0) continue; if (sh->offset != subvol_id) continue; - body = (uint8_t*) sh + sizeof(struct btrfs_ioctl_search_header); - if (sh->type == BTRFS_QGROUP_INFO_KEY) { - const struct btrfs_qgroup_info_item *qii = body; + const struct btrfs_qgroup_info_item *qii = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh); - ret->referred = le64toh(qii->rfer); + ret->referenced = le64toh(qii->rfer); ret->exclusive = le64toh(qii->excl); found_info = true; } else if (sh->type == BTRFS_QGROUP_LIMIT_KEY) { - const struct btrfs_qgroup_limit_item *qli = body; + const struct btrfs_qgroup_limit_item *qli = BTRFS_IOCTL_SEARCH_HEADER_BODY(sh); - ret->referred_max = le64toh(qli->max_rfer); + ret->referenced_max = le64toh(qli->max_rfer); ret->exclusive_max = le64toh(qli->max_excl); - if (ret->referred_max == 0) - ret->referred_max = (uint64_t) -1; + if (ret->referenced_max == 0) + ret->referenced_max = (uint64_t) -1; if (ret->exclusive_max == 0) ret->exclusive_max = (uint64_t) -1; @@ -510,8 +587,8 @@ int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *ret) { goto finish; } - args.key.min_offset++; - if (!args.key.min_offset) + /* Increase search key by one, to read the next item, if we can. */ + if (!btrfs_ioctl_search_args_inc(&args)) break; } @@ -520,14 +597,556 @@ finish: return -ENODATA; if (!found_info) { - ret->referred = (uint64_t) -1; + ret->referenced = (uint64_t) -1; ret->exclusive = (uint64_t) -1; } if (!found_limit) { - ret->referred_max = (uint64_t) -1; + ret->referenced_max = (uint64_t) -1; ret->exclusive_max = (uint64_t) -1; } return 0; } + +int btrfs_defrag_fd(int fd) { + struct stat st; + + assert(fd >= 0); + + if (fstat(fd, &st) < 0) + return -errno; + + if (!S_ISREG(st.st_mode)) + return -EINVAL; + + if (ioctl(fd, BTRFS_IOC_DEFRAG, NULL) < 0) + return -errno; + + return 0; +} + +int btrfs_defrag(const char *p) { + _cleanup_close_ int fd = -1; + + fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); + if (fd < 0) + return -errno; + + return btrfs_defrag_fd(fd); +} + +int btrfs_quota_enable_fd(int fd, bool b) { + struct btrfs_ioctl_quota_ctl_args args = { + .cmd = b ? BTRFS_QUOTA_CTL_ENABLE : BTRFS_QUOTA_CTL_DISABLE, + }; + int r; + + assert(fd >= 0); + + r = btrfs_is_filesystem(fd); + if (r < 0) + return r; + if (!r) + return -ENOTTY; + + if (ioctl(fd, BTRFS_IOC_QUOTA_CTL, &args) < 0) + return -errno; + + return 0; +} + +int btrfs_quota_enable(const char *path, bool b) { + _cleanup_close_ int fd = -1; + + fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); + if (fd < 0) + return -errno; + + return btrfs_quota_enable_fd(fd, b); +} + +int btrfs_quota_limit_fd(int fd, uint64_t referenced_max) { + struct btrfs_ioctl_qgroup_limit_args args = { + .lim.max_rfer = + referenced_max == (uint64_t) -1 ? 0 : + referenced_max == 0 ? 1 : referenced_max, + .lim.flags = BTRFS_QGROUP_LIMIT_MAX_RFER, + }; + int r; + + assert(fd >= 0); + + r = btrfs_is_filesystem(fd); + if (r < 0) + return r; + if (!r) + return -ENOTTY; + + if (ioctl(fd, BTRFS_IOC_QGROUP_LIMIT, &args) < 0) + return -errno; + + return 0; +} + +int btrfs_quota_limit(const char *path, uint64_t referenced_max) { + _cleanup_close_ int fd = -1; + + fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); + if (fd < 0) + return -errno; + + return btrfs_quota_limit_fd(fd, referenced_max); +} + +int btrfs_resize_loopback_fd(int fd, uint64_t new_size, bool grow_only) { + struct btrfs_ioctl_vol_args args = {}; + _cleanup_free_ char *p = NULL, *loop = NULL, *backing = NULL; + _cleanup_close_ int loop_fd = -1, backing_fd = -1; + struct stat st; + dev_t dev = 0; + int r; + + /* btrfs cannot handle file systems < 16M, hence use this as minimum */ + if (new_size < 16*1024*1024) + new_size = 16*1024*1024; + + r = btrfs_get_block_device_fd(fd, &dev); + if (r < 0) + return r; + if (r == 0) + return -ENODEV; + + if (asprintf(&p, "/sys/dev/block/%u:%u/loop/backing_file", major(dev), minor(dev)) < 0) + return -ENOMEM; + r = read_one_line_file(p, &backing); + if (r == -ENOENT) + return -ENODEV; + if (r < 0) + return r; + if (isempty(backing) || !path_is_absolute(backing)) + return -ENODEV; + + backing_fd = open(backing, O_RDWR|O_CLOEXEC|O_NOCTTY); + if (backing_fd < 0) + return -errno; + + if (fstat(backing_fd, &st) < 0) + return -errno; + if (!S_ISREG(st.st_mode)) + return -ENODEV; + + if (new_size == (uint64_t) st.st_size) + return 0; + + if (grow_only && new_size < (uint64_t) st.st_size) + return -EINVAL; + + if (asprintf(&loop, "/dev/block/%u:%u", major(dev), minor(dev)) < 0) + return -ENOMEM; + loop_fd = open(loop, O_RDWR|O_CLOEXEC|O_NOCTTY); + if (loop_fd < 0) + return -errno; + + if (snprintf(args.name, sizeof(args.name), "%" PRIu64, new_size) >= (int) sizeof(args.name)) + return -EINVAL; + + if (new_size < (uint64_t) st.st_size) { + /* Decrease size: first decrease btrfs size, then shorten loopback */ + if (ioctl(fd, BTRFS_IOC_RESIZE, &args) < 0) + return -errno; + } + + if (ftruncate(backing_fd, new_size) < 0) + return -errno; + + if (ioctl(loop_fd, LOOP_SET_CAPACITY, 0) < 0) + return -errno; + + if (new_size > (uint64_t) st.st_size) { + /* Increase size: first enlarge loopback, then increase btrfs size */ + if (ioctl(fd, BTRFS_IOC_RESIZE, &args) < 0) + return -errno; + } + + /* Make sure the free disk space is correctly updated for both file systems */ + (void) fsync(fd); + (void) fsync(backing_fd); + + return 1; +} + +int btrfs_resize_loopback(const char *p, uint64_t new_size, bool grow_only) { + _cleanup_close_ int fd = -1; + + fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC); + if (fd < 0) + return -errno; + + 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; + struct stat st; + bool made_writable = false; + int r; + + assert(fd >= 0); + assert(subvolume); + + if (fstat(fd, &st) < 0) + return -errno; + + if (!S_ISDIR(st.st_mode)) + return -EINVAL; + + /* 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 = htole64(ref->dirid); + + if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0) + return -errno; + + if (!made_writable) { + r = btrfs_subvol_set_read_only_fd(subvol_fd, false); + if (r < 0) + return r; + + made_writable = true; + } + + 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); +} + +static int subvol_snapshot_children(int old_fd, int new_fd, const char *subvolume, uint64_t subvol_id, BtrfsSnapshotFlags flags) { + + 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_v2 vol_args = { + .flags = flags & BTRFS_SNAPSHOT_READ_ONLY ? BTRFS_SUBVOL_RDONLY : 0, + .fd = old_fd, + }; + int r; + _cleanup_close_ int subvolume_fd = -1; + + assert(old_fd >= 0); + assert(new_fd >= 0); + assert(subvolume); + + strncpy(vol_args.name, subvolume, sizeof(vol_args.name)-1); + vol_args.fd = old_fd; + + if (ioctl(new_fd, BTRFS_IOC_SNAP_CREATE_V2, &vol_args) < 0) + return -errno; + + if (!(flags & BTRFS_SNAPSHOT_RECURSIVE)) + return 0; + + if (subvol_id == 0) { + r = btrfs_subvol_get_id_fd(old_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(old_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, *c = NULL, *np = NULL; + struct btrfs_ioctl_ino_lookup_args ino_args; + const struct btrfs_root_ref *ref; + _cleanup_close_ int old_child_fd = -1, new_child_fd = -1; + + 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 = htole64(ref->dirid); + + if (ioctl(old_fd, BTRFS_IOC_INO_LOOKUP, &ino_args) < 0) + return -errno; + + /* The kernel returns an empty name if the + * subvolume is in the top-level directory, + * and otherwise appends a slash, so that we + * can just concatenate easily here, without + * adding a slash. */ + c = strappend(ino_args.name, p); + if (!c) + return -ENOMEM; + + old_child_fd = openat(old_fd, c, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (old_child_fd < 0) + return -errno; + + np = strjoin(subvolume, "/", ino_args.name, NULL); + if (!np) + return -ENOMEM; + + new_child_fd = openat(new_fd, np, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (new_child_fd < 0) + return -errno; + + if (flags & BTRFS_SNAPSHOT_READ_ONLY) { + /* If the snapshot is read-only we + * need to mark it writable + * temporarily, to put the subsnapshot + * into place. */ + + if (subvolume_fd < 0) { + subvolume_fd = openat(new_fd, subvolume, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (subvolume_fd < 0) + return -errno; + } + + r = btrfs_subvol_set_read_only_fd(subvolume_fd, false); + if (r < 0) + return r; + } + + /* When btrfs clones the subvolumes, child + * subvolumes appear as directories. Remove + * them, so that we can create a new snapshot + * in their place */ + if (unlinkat(new_child_fd, p, AT_REMOVEDIR) < 0) { + int k = -errno; + + if (flags & BTRFS_SNAPSHOT_READ_ONLY) + (void) btrfs_subvol_set_read_only_fd(subvolume_fd, true); + + return k; + } + + r = subvol_snapshot_children(old_child_fd, new_child_fd, p, sh->objectid, flags & ~BTRFS_SNAPSHOT_FALLBACK_COPY); + + /* Restore the readonly flag */ + if (flags & BTRFS_SNAPSHOT_READ_ONLY) { + int k; + + k = btrfs_subvol_set_read_only_fd(subvolume_fd, true); + if (r >= 0 && k < 0) + return k; + } + + 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; + } + + return 0; +} + +int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, BtrfsSnapshotFlags flags) { + _cleanup_close_ int new_fd = -1; + const char *subvolume; + int r; + + assert(old_fd >= 0); + assert(new_path); + + r = btrfs_is_subvol(old_fd); + if (r < 0) + return r; + if (r == 0) { + if (!(flags & BTRFS_SNAPSHOT_FALLBACK_COPY)) + return -EISDIR; + + r = btrfs_subvol_make(new_path); + if (r < 0) + return r; + + r = copy_directory_fd(old_fd, new_path, true); + if (r < 0) { + btrfs_subvol_remove(new_path, false); + return r; + } + + if (flags & BTRFS_SNAPSHOT_READ_ONLY) { + r = btrfs_subvol_set_read_only(new_path, true); + if (r < 0) { + btrfs_subvol_remove(new_path, false); + return r; + } + } + + return 0; + } + + r = extract_subvolume_name(new_path, &subvolume); + if (r < 0) + return r; + + new_fd = open_parent(new_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (new_fd < 0) + return new_fd; + + return subvol_snapshot_children(old_fd, new_fd, subvolume, 0, flags); +} + +int btrfs_subvol_snapshot(const char *old_path, const char *new_path, BtrfsSnapshotFlags flags) { + _cleanup_close_ int old_fd = -1; + + assert(old_path); + assert(new_path); + + old_fd = open(old_path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY); + if (old_fd < 0) + return -errno; + + return btrfs_subvol_snapshot_fd(old_fd, new_path, flags); +}