From 5743a5852d2ab6ad7f589c255afcfdf523d60ba8 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 7 Jan 2015 14:43:10 +0100 Subject: [PATCH] btrfs-util: rework how we iterate through the results of the TREE_SEARCH results Let's introduce some syntactic sugar with iteration macros, and add correct key increment calls. --- src/shared/btrfs-util.c | 127 ++++++++++++++++++++++++++++++---------- 1 file changed, 95 insertions(+), 32 deletions(-) diff --git a/src/shared/btrfs-util.c b/src/shared/btrfs-util.c index e648121b4..bd100eef0 100644 --- a/src/shared/btrfs-util.c +++ b/src/shared/btrfs-util.c @@ -338,6 +338,77 @@ 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 +418,10 @@ 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 +439,7 @@ 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 +450,23 @@ 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 +482,8 @@ 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 +500,14 @@ 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 +526,7 @@ 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; @@ -466,26 +537,18 @@ 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->exclusive = le64toh(qii->excl); @@ -493,7 +556,7 @@ int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *ret) { 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->exclusive_max = le64toh(qli->max_excl); @@ -510,8 +573,8 @@ 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; } -- 2.30.2