Now the source file is coming.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
diff-snapshot.c | 1026 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1026 insertions(+), 0 deletions(-)
create mode 100644 diff-snapshot.c
diff --git a/diff-snapshot.c b/diff-snapshot.c
new file mode 100644
index 0000000..7b7f4c7
--- /dev/null
+++ b/diff-snapshot.c
@@ -0,0 +1,1026 @@
+/*
+ * Copyright (C) 2012 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <uuid/uuid.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+#include "ctree.h"
+#include "ioctl.h"
+#include "utils.h"
+#include "btrfs-list.h"
+#include "diff-snapshot.h"
+
+/*
+ * scan and cache the number of items from both snapshots at a time.
+ * FIXME: maybe it''s better to let user to specify this value
according
+ * to their memory status, cache more items every time can improve the
+ * overall performance as it could reduce the efforts to retrieve items
+ * through ioctl(2). or we can implement a routine to calculate this value
+ * based on the available memory, maybe sounds more reasonable.
+ */
+static unsigned int nr_item_scan = 4096;
+
+struct snapshot_diff_info {
+ /* source snapshot scan info */
+ struct snapshot_scan_info *src_scan_info;
+
+ /* destination snapshot scan info */
+ struct snapshot_scan_info *dest_scan_info;
+};
+
+struct snapshot_scan_info {
+ /* name */
+ char *snapshot;
+
+ /* snapshot dir id */
+ int fd;
+
+ /* snapshot tree id */
+ u64 tree_id;
+
+ /* the latest object id in last round of scan */
+ u64 last_objectid;
+
+ /* cache the scanned items on */
+ struct rb_root scanned_items;
+
+ /*
+ * rb-tree to cache those items which have already been
+ * processed by lookup snapshot, so it will not be cached
+ * again. the memory allocated for it would be reclaimed
+ * back once we determined that the business for it was
+ * done.
+ */
+ struct rb_root processed_items;
+
+ /* no more items can be fetched from a snapshot */
+ int scan_done;
+};
+
+/* item info at cache */
+struct snapshot_scan_item {
+ struct rb_node si_node;
+ u64 transid;
+ u64 objectid;
+ char *path;
+ u8 type;
+};
+
+/*
+ * processed items are those who are not returned in the current
+ * round of scan, but they are resides on snapshot.
+ */
+struct processed_item {
+ struct rb_node pi_node;
+ char *path;
+};
+
+static const char *decode_item_type(u8 type)
+{
+ char *typestr = "UNKNOWN";
+
+ switch (type) {
+ case BTRFS_FT_DIR:
+ typestr = "DIR";
+ break;
+ case BTRFS_FT_REG_FILE:
+ typestr = "REGFILE";
+ break;
+ case BTRFS_FT_CHRDEV:
+ typestr = "CHRDEV";
+ break;
+ case BTRFS_FT_BLKDEV:
+ typestr = "BLKDEV";
+ break;
+ case BTRFS_FT_FIFO:
+ typestr = "FIFO";
+ break;
+ case BTRFS_FT_SOCK:
+ typestr = "SOCKET";
+ break;
+ case BTRFS_FT_SYMLINK:
+ typestr = "SYMLINK";
+ break;
+ case BTRFS_FT_XATTR:
+ typestr = "XATTR";
+ break;
+ default:
+ break;
+ }
+
+ return typestr;
+}
+
+/*
+ * we found an item on both snapshots, check if it was updated or not
+ * by comparing ctime && mtime.
+ */
+static inline int item_is_updated(const char *src_snapshot,
+ const char *dest_snapshot,
+ const char *path, u8 item_type,
+ int *updated)
+{
+ char src_full_path[BTRFS_PATH_NAME_MAX + 1];
+ char dest_full_path[BTRFS_PATH_NAME_MAX + 1];
+ struct stat st1;
+ struct stat st2;
+ int ret = 0;
+
+ ret = snprintf(src_full_path, sizeof(src_full_path), "%s/%s",
+ src_snapshot, path);
+ if (ret < 0) {
+ fprintf(stderr, "failed to build full path [%s/%s]\n",
+ src_snapshot, path);
+ goto out;
+ }
+
+ ret = snprintf(dest_full_path, sizeof(dest_full_path), "%s/%s",
+ dest_snapshot, path);
+ if (ret < 0) {
+ fprintf(stderr, "failed to build full path [%s/%s]\n",
+ dest_snapshot, path);
+ goto out;
+ }
+
+ if (item_type == BTRFS_FT_SYMLINK) {
+ if (lstat(src_full_path, &st1) < 0) {
+ fprintf(stderr, "lstat %s failed %s\n",
+ src_full_path, strerror(errno));
+ ret = -1;
+ goto out;
+ }
+
+ if (lstat(dest_full_path, &st2) < 0) {
+ fprintf(stderr, "lstat %s failed %s\n",
+ dest_full_path, strerror(errno));
+ ret = -1;
+ goto out;
+ }
+ } else {
+ if (stat(src_full_path, &st1) < 0) {
+ fprintf(stderr, "stat src path %s failed %s\n",
+ src_full_path, strerror(errno));
+ ret = -1;
+ goto out;
+ }
+
+ if (stat(dest_full_path, &st2) < 0) {
+ fprintf(stderr, "stat dest path %s failed %s\n",
+ dest_full_path, strerror(errno));
+ ret = -1;
+ goto out;
+ }
+ }
+
+ *updated = (st1.st_mtime != st2.st_mtime ||
+ st1.st_ctime != st2.st_ctime) ? 1 : 0;
+
+out:
+ return ret;
+}
+
+static const char *decode_item_state(unsigned int state)
+{
+ char *s = NULL;
+
+ switch (state) {
+ case SNAPSHOT_DIFF_NEW_ITEM:
+ s = "NEW";
+ break;
+ case SNAPSHOT_DIFF_REMOVED_ITEM:
+ s = "REMOVED";
+ break;
+ case SNAPSHOT_DIFF_UPDATED_ITEM:
+ s = "UPDATED";
+ break;
+ default:
+ break;
+ }
+
+ return s;
+}
+
+static inline void print_item_diff_info(struct snapshot_scan_item *item,
+ const char *snapshot,
+ unsigned int state)
+{
+ const char *s = decode_item_state(state);
+ const char *type = decode_item_type(item->type);
+
+ printf("[%s %s] %s/%s objectid %llu transid %llu\n",
+ s, type, snapshot, item->path, item->objectid,
+ item->transid);
+}
+
+static inline int snapshot_diff_init(struct snapshot_diff_info *diff_info)
+
+{
+ diff_info->src_scan_info = malloc(sizeof(struct snapshot_scan_info));
+ if (!diff_info->src_scan_info)
+ return -ENOMEM;
+
+ diff_info->dest_scan_info = malloc(sizeof(struct snapshot_scan_info));
+ if (!diff_info->dest_scan_info)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static inline int snapshot_item_scan_init(struct snapshot_scan_info *scan_info,
+ const char *snapshot, int fd,
+ u64 tree_id)
+{
+ scan_info->snapshot = strdup(snapshot);
+ if (!scan_info->snapshot)
+ return -ENOMEM;
+
+ scan_info->fd = fd;
+ scan_info->tree_id = tree_id;
+ scan_info->last_objectid = 256;
+ scan_info->scan_done = 0;
+ scan_info->scanned_items = RB_ROOT;
+ scan_info->processed_items = RB_ROOT;
+}
+
+static u64 get_snapshot_tree_id(int fd)
+{
+ struct btrfs_ioctl_ino_lookup_args ino_args;
+ int ret;
+
+ memset(&ino_args, 0, sizeof(ino_args));
+ ino_args.objectid = BTRFS_FIRST_FREE_OBJECTID;
+
+ ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args);
+ if (ret) {
+ fprintf(stderr,
+ "ERROR: Failed to lookup path for dirid %llu - %s\n",
+ (unsigned long long)BTRFS_FIRST_FREE_OBJECTID,
+ strerror(errno));
+ return 0;
+ }
+
+ return ino_args.treeid;
+}
+
+static int cache_processed_item(struct rb_root *root, const char *path)
+{
+ struct rb_node **p = &(root->rb_node);
+ struct rb_node *parent = NULL;
+ struct processed_item *item;
+
+ while (*p) {
+ int ret;
+ struct processed_item *this;
+ this = rb_entry(*p, struct processed_item, pi_node);
+ parent = *p;
+ ret = strcmp(this->path, path);
+ if (ret > 0)
+ p = &(*p)->rb_left;
+ else if (ret < 0)
+ p = &(*p)->rb_right;
+ else
+ /*
+ * FIXME: to handle this situation in a
+ * more reasonable way.
+ */
+ return 0;
+ }
+
+ item = calloc(1, sizeof(*item));
+ item->path = strdup(path);
+ if (!item->path) {
+ fprintf(stderr, "out of memory to cache processed item\n");
+ return -ENOMEM;
+ }
+
+ rb_link_node(&item->pi_node, parent, p);
+ rb_insert_color(&item->pi_node, root);
+
+ return 0;
+}
+
+static struct processed_item *find_processed_item(struct rb_root *root,
+ const char *path)
+{
+ struct rb_node *node = rb_first(root);
+ struct processed_item *this;
+
+ while (node) {
+ int ret;
+ this = rb_entry(node, struct processed_item, pi_node);
+ ret = strcmp(this->path, path);
+ if (ret > 0)
+ node = node->rb_left;
+ else if (ret < 0)
+ node = node->rb_right;
+ else
+ return this;
+ }
+
+ return NULL;
+}
+
+static void remove_processed_item(struct rb_root *root, const char *path)
+{
+ struct processed_item *item;
+
+ item = find_processed_item(root, path);
+ if (item) {
+ rb_erase(&item->pi_node, root);
+ free(item->path);
+ free(item);
+ }
+}
+
+static int item_is_processed(struct rb_root *root, const char *path)
+{
+ return find_processed_item(root, path) ? 1 : 0;
+}
+
+static void free_processed_items(struct rb_root *root)
+{
+ struct processed_item *item;
+ struct rb_node *node;
+
+ while ((node = rb_first(root))) {
+ item = rb_entry(node, struct processed_item, pi_node);
+ rb_erase(&item->pi_node, root);
+ free(item->path);
+ free(item);
+ }
+}
+
+static void snapshot_item_scan_free(struct snapshot_scan_info *scan_info)
+{
+ struct rb_root *root = &scan_info->scanned_items;
+ struct snapshot_scan_item *item;
+ struct rb_node *node;
+
+ while ((node = rb_first(root))) {
+ item = rb_entry(node, struct snapshot_scan_item, si_node);
+ rb_erase(&item->si_node, root);
+ free(item->path);
+ free(item);
+ }
+}
+
+static inline void
+snapshot_diff_destroy(struct snapshot_diff_info *diff_info)
+{
+ struct snapshot_scan_info *src_scan_info = diff_info->src_scan_info;
+ struct snapshot_scan_info *dest_scan_info = diff_info->dest_scan_info;
+
+ free(src_scan_info->snapshot);
+ free(dest_scan_info->snapshot);
+
+ free_processed_items(&src_scan_info->processed_items);
+ free_processed_items(&dest_scan_info->processed_items);
+
+ snapshot_item_scan_free(diff_info->src_scan_info);
+ snapshot_item_scan_free(diff_info->dest_scan_info);
+
+ free(src_scan_info);
+ free(dest_scan_info);
+}
+
+static int add_item_to_cache(struct rb_root *root, const char *path, u8 type,
+ u64 objectid, u64 transid)
+{
+ struct rb_node **p = &(root->rb_node);
+ struct rb_node *parent = NULL;
+ struct snapshot_scan_item *item;
+
+ while (*p) {
+ struct snapshot_scan_item *this;
+ int ret;
+
+ this = rb_entry(*p, struct snapshot_scan_item, si_node);
+ parent = *p;
+ ret = strcmp(this->path, path);
+ if (ret > 0)
+ p = &(*p)->rb_left;
+ else if (ret < 0)
+ p = &(*p)->rb_right;
+ else
+ assert(0);
+ }
+
+ item = malloc(sizeof(struct snapshot_scan_item));
+ if (!item) {
+ fprintf(stderr, "out of memory while inserting new item\n");
+ return -ENOMEM;
+ }
+
+ item->path = strdup(path);
+ if (!item->path) {
+ fprintf(stderr, "out of memory while inserting new item\n");
+ return -ENOMEM;
+ }
+
+ item->type = type;
+ item->objectid = objectid;
+ item->transid = transid;
+
+ rb_link_node(&item->si_node, parent, p);
+ rb_insert_color(&item->si_node, root);
+ return 0;
+}
+
+static int process_snapshot_item(struct snapshot_scan_info *scan_info,
+ struct btrfs_dir_item *item)
+{
+ struct rb_root *processed_items = &scan_info->processed_items;
+ struct rb_root *scanned_items = &scan_info->scanned_items;
+ char *cache_dir_name = NULL;
+ int fd = scan_info->fd;
+ char *path;
+ u64 cache_dirid;
+ int ret = 0;
+
+ path = ino_resolve(fd, item->location.objectid,
+ &cache_dirid, &cache_dir_name);
+ if (!path) {
+ ret = -EIO;
+ goto out;
+ }
+
+ /*
+ * this item can be freely skipped as we have already processed
+ * it in previous business.
+ */
+ if (item_is_processed(processed_items, path)) {
+ remove_processed_item(processed_items, path);
+ goto out;
+ }
+
+ ret = add_item_to_cache(scanned_items, path, item->type,
+ item->location.objectid,
+ item->transid);
+
+out:
+ return ret;
+}
+
+static int do_snapshot_scan(struct snapshot_scan_info *scan_info)
+{
+ struct btrfs_ioctl_search_args args;
+ struct btrfs_ioctl_search_key *sk = &args.key;
+ struct btrfs_ioctl_search_header *sh;
+ struct btrfs_dir_item *item;
+ struct btrfs_dir_item backup;
+ int fd = scan_info->fd;
+ int count = 0;
+ int ret;
+
+ memset(&backup, 0, sizeof(backup));
+ memset(&args, 0, sizeof(args));
+
+ sk->tree_id = scan_info->tree_id;
+ sk->min_objectid = scan_info->last_objectid;
+ sk->min_type = BTRFS_DIR_INDEX_KEY;
+ sk->max_type = BTRFS_DIR_INDEX_KEY;
+
+ /*
+ * set all the other params to the max, we''ll take any objectid
+ * and any trans
+ */
+ sk->max_objectid = (u64)-1;
+ sk->max_offset = (u64)-1;
+ sk->max_transid = (u64)-1;
+
+ /* just a big number, doesn''t matter much */
+ sk->nr_items = 4096;
+
+ do {
+ unsigned long off = 0;
+ int i;
+ ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: can''t perform the search %s\n",
+ strerror(errno));
+ return ret;
+ }
+
+ /* the ioctl returns the number of item it found in nr_items */
+ if (sk->nr_items == 0) {
+ scan_info->scan_done = true;
+ break;
+ }
+
+ /*
+ * for each item, pull the key out of the header and then
+ * read the root_ref item it contains
+ */
+ for (i = 0; i < sk->nr_items; i++) {
+ sh = (struct btrfs_ioctl_search_header *)(args.buf +
+ off);
+ off += sizeof(*sh);
+
+ /*
+ * just in case the item was too big, pass something
+ * other than garbage
+ */
+ if (sh->len == 0)
+ item = &backup;
+ else
+ item = (struct btrfs_dir_item *)(args.buf +
+ off);
+
+ if (sh->type == BTRFS_DIR_INDEX_KEY) {
+ ret = process_snapshot_item(scan_info, item);
+ if (ret < 0)
+ return ret;
+ ++count;
+ }
+
+ off += sh->len;
+
+ /*
+ * record the mins in sk so we can make sure the
+ * next search doesn''t repeat this root
+ */
+ sk->min_objectid = sh->objectid;
+ sk->min_offset = sh->offset;
+ sk->min_type = sh->type;
+ }
+
+ if (sk->min_offset < (u64)-1) {
+ sk->min_offset++;
+ } else if (sk->min_objectid < (u64)-1) {
+ sk->min_objectid++;
+ sk->min_offset = 0;
+ sk->min_type = 0;
+ } else {
+ scan_info->scan_done = 1;
+ break;
+ }
+ } while (count < nr_item_scan);
+
+ if (!scan_info->scan_done)
+ scan_info->last_objectid = sk->min_objectid;
+
+ return ret;
+}
+
+static int snapshot_item_scan_read(struct snapshot_scan_info *scan_info)
+{
+ return do_snapshot_scan(scan_info);
+}
+
+static struct snapshot_scan_item *find_item_on_cache(struct rb_root *root,
+ const char *path)
+{
+ struct rb_node *node = rb_first(root);
+ struct snapshot_scan_item *this;
+
+ while (node) {
+ int ret;
+ this = rb_entry(node, struct snapshot_scan_item, si_node);
+ ret = strcmp(this->path, path);
+ if (ret > 0)
+ node = node->rb_left;
+ else if (ret < 0)
+ node = node->rb_right;
+ else
+ return this;
+ }
+
+ return NULL;
+}
+
+static void remove_item_from_cache(struct rb_root *root, const char *path)
+{
+ struct snapshot_scan_item *item;
+
+ item = find_item_on_cache(root, path);
+ if (item) {
+ rb_erase(&item->si_node, root);
+ free(item->path);
+ free(item);
+ }
+}
+
+/* check if an item path does exist on dest snapshot or not */
+static inline int find_item_on_snapshot(const char *path, u8 type, int *found)
+{
+ int ret;
+
+ if (type != BTRFS_FT_SYMLINK) {
+ ret = access(path, F_OK);
+ if (ret == 0) {
+ *found = 1;
+ goto out;
+ }
+
+ if (errno == ENOENT) {
+ *found = 0;
+ ret = 0;
+ goto out;
+ }
+ fprintf(stderr, "failed to access %s as %s\n",
+ path, strerror(errno));
+ } else {
+ struct stat st;
+ ret = lstat(path, &st);
+ if (ret == 0) {
+ *found = 1;
+ goto out;
+ }
+
+ if (errno == ENOENT) {
+ *found = 0;
+ ret = 0;
+ goto out;
+ }
+ fprintf(stderr, "failed to lstat %s failed as %s\n",
+ path, strerror(errno));
+ }
+
+out:
+ return ret;
+}
+
+static int do_item_diff(struct snapshot_scan_item *item, u8 item_type,
+ unsigned int item_state, const char *src_snapshot,
+ const char *dest_snapshot, unsigned int flags)
+{
+ int updated;
+ int ret = 0;
+
+ switch (item_state) {
+ case SNAPSHOT_DIFF_NEW_ITEM:
+ if (SNAPSHOT_DIFF_SHOW_NEW_ITEM(flags))
+ print_item_diff_info(item, dest_snapshot, item_state);
+ break;
+ case SNAPSHOT_DIFF_REMOVED_ITEM:
+ if (SNAPSHOT_DIFF_SHOW_REMOVED_ITEM(flags))
+ print_item_diff_info(item, src_snapshot, item_state);
+ break;
+ case SNAPSHOT_DIFF_UPDATED_ITEM:
+ if (SNAPSHOT_DIFF_SHOW_UPDATED_ITEM(flags)) {
+ ret = item_is_updated(src_snapshot, dest_snapshot,
+ item->path, item_type, &updated);
+ if (ret < 0)
+ return ret;
+
+ if (updated) {
+ print_item_diff_info(item, dest_snapshot,
+ item_state);
+ }
+ }
+ break;
+ default:
+ assert(0);
+ }
+
+ return ret;
+}
+
+static int inline build_full_path(char full_path[BTRFS_PATH_NAME_MAX + 1],
+ const char *src_snapshot,
+ const char *path)
+{
+ size_t len = strlen(src_snapshot) + strlen(path) + 1;
+
+ if (snprintf(full_path, BTRFS_PATH_NAME_MAX + 1, "%s/%s",
+ src_snapshot, path) != len) {
+ fprintf(stderr, "failed to build full path %s/%s\n",
+ src_snapshot, path);
+ return -1;
+ }
+
+ return 0;
+}
+
+
+/*
+ * step through each scanned item from source cache, and check it up on dest
+ * cache firstly. if an item can be found at dest cache and if it does not
+ * changed by examining its ctime and mtime upon the source one, proceed to
+ * check the next source item, or print the updated info if needed.
+ * if we can not find it at the dest cache, probably it resides on the dest
+ * snapshot, hence, we need to check it up on there. if it does not exist,
+ * print the removed info if needed, otherwise, check if it was updated or not.
+ */
+static int process_source_item_cache(struct snapshot_scan_info *src_scan_info,
+ struct snapshot_scan_info *dest_scan_info,
+ unsigned int flags)
+{
+ struct rb_root *src_scanned_items = &src_scan_info->scanned_items;
+ struct rb_root *dest_scanned_items = &dest_scan_info->scanned_items;
+ struct rb_root *processed_items = &dest_scan_info->processed_items;
+ const char *src_snapshot = src_scan_info->snapshot;
+ const char *dest_snapshot = dest_scan_info->snapshot;
+ struct rb_node *node;
+ u8 item_type;
+ int ret = 0;
+
+ for (node = rb_first(src_scanned_items); node; node = rb_next(node)) {
+ char full_path[BTRFS_PATH_NAME_MAX + 1];
+ struct snapshot_scan_item *src_item;
+ struct snapshot_scan_item *dest_item;
+ unsigned int item_state;
+ const char *path;
+ int found = 0;
+
+ src_item = rb_entry(node, struct snapshot_scan_item, si_node);
+ item_type = src_item->type;
+ path = src_item->path;
+
+ /* can it be found on dest cache? */
+ dest_item = find_item_on_cache(dest_scanned_items, path);
+ if (dest_item) {
+ item_state = SNAPSHOT_DIFF_UPDATED_ITEM,
+ ret = do_item_diff(src_item, item_type, item_state,
+ src_snapshot, dest_snapshot, flags);
+ if (ret < 0)
+ break;
+
+ continue;
+ }
+
+ ret = build_full_path(full_path, dest_snapshot, path);
+ if (ret < 0)
+ break;
+
+ /*
+ * the source item was not found from dest cache. probably
+ * it resides at dest snapshot, try to lookup it there so.
+ */
+ ret = find_item_on_snapshot(full_path, item_type, &found);
+ if (ret < 0)
+ break;
+
+ item_state = found ? SNAPSHOT_DIFF_UPDATED_ITEM :
+ SNAPSHOT_DIFF_REMOVED_ITEM;
+ ret = do_item_diff(src_item, item_type, item_state,
+ src_snapshot, dest_snapshot, flags);
+ if (ret < 0)
+ break;
+
+ /*
+ * so we found the source item from the dest snapshot,
+ * however, it will be retrieved again when scanning
+ * the dest snapshot at a later time. to avoid this,
+ * we should put it to the dest processed tree, so it
+ * will be skipped to cache again at that time.
+ */
+ if (found) {
+ ret = cache_processed_item(processed_items, path);
+ if (ret < 0)
+ break;
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * revert to iterate the left items in dest cache and find out whether it
+ * resides on source snapshot or not. note that, those left items must not
+ * exists on source cache as we have already done that check up. so we only
+ * need to examine if it does exist on source subvolume or not. if not, a
+ * a new created item was found. otherwise, check it was updated or not.
+ */
+static int process_dest_item_cache(struct snapshot_scan_info *src_scan_info,
+ struct snapshot_scan_info *dest_scan_info,
+ int flags)
+{
+ struct rb_root *scanned_items = &dest_scan_info->scanned_items;
+ struct rb_root *processed_items = &src_scan_info->processed_items;
+ const char *src_snapshot = src_scan_info->snapshot;
+ const char *dest_snapshot = dest_scan_info->snapshot;
+ struct rb_node *node;
+ int ret = 0;
+
+ for (node = rb_first(scanned_items); node; node = rb_next(node)) {
+ char full_path[BTRFS_PATH_NAME_MAX + 1];
+ struct snapshot_scan_item *item;
+ unsigned int item_state;
+ const char *path;
+ u8 item_type;
+ int found = 0;
+
+ item = rb_entry(node, struct snapshot_scan_item, si_node);
+ path = item->path;
+
+ ret = build_full_path(full_path, src_snapshot, path);
+ if (ret < 0)
+ break;
+
+ item_type = item->type;
+ /* check if this item located at source snapshot or not */
+ ret = find_item_on_snapshot(full_path, item_type, &found);
+ if (ret < 0)
+ break;
+
+ item_state = found ? SNAPSHOT_DIFF_UPDATED_ITEM :
+ SNAPSHOT_DIFF_NEW_ITEM;
+ ret = do_item_diff(item, item_type, item_state, src_snapshot,
+ dest_snapshot, flags);
+ if (ret < 0)
+ break;
+
+ /*
+ * so we found this time on the source snapshot. put it to
+ * processed tree so we''ll not cache and handle it again.
+ */
+ if (found) {
+ ret = cache_processed_item(processed_items, path);
+ if (ret < 0)
+ break;
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * so we have two caches holding the scanned items from both source and
+ * dest snapshot, perform real diff business now.
+ */
+static int do_diff_items(struct snapshot_scan_info *src_scan_info,
+ struct snapshot_scan_info *dest_scan_info,
+ unsigned int flags)
+{
+ int ret = 0;
+
+ ret = process_source_item_cache(src_scan_info, dest_scan_info, flags);
+ if (ret < 0)
+ return ret;
+
+ ret = process_dest_item_cache(src_scan_info, dest_scan_info, flags);
+ return ret;
+}
+
+int snapshot_diff(int src_fd, int dest_fd, const char *src_snapshot,
+ const char *dest_snapshot, unsigned int flags)
+{
+ struct snapshot_diff_info diff_info;
+ struct snapshot_scan_info *src_scan_info;
+ struct snapshot_scan_info *dest_scan_info;
+ u64 src_tree_id;
+ u64 dest_tree_id;
+ int diff_done = 0;
+ int ret;
+
+ /*
+ * commit buffer cache to disk to make the new transactions
+ * of both snapshots take affected immediately.
+ */
+ sync();
+
+ src_tree_id = get_snapshot_tree_id(src_fd);
+ if (!src_tree_id)
+ return 1;
+
+ dest_tree_id = get_snapshot_tree_id(dest_fd);
+ if (!dest_tree_id)
+ return 1;
+
+ /*
+ * list all changes on the dest snapshot if no option
+ * was specified.
+ */
+ if (!flags) {
+ flags |= (SNAPSHOT_DIFF_LIST_NEW_ITEM |
+ SNAPSHOT_DIFF_LIST_REMOVED_ITEM |
+ SNAPSHOT_DIFF_LIST_UPDATED_ITEM);
+ }
+
+ ret = snapshot_diff_init(&diff_info);
+ if (ret < 0) {
+ fprintf(stderr, "snapshot diff init failed\n");
+ return ret;
+ }
+
+ src_scan_info = diff_info.src_scan_info;
+ dest_scan_info = diff_info.dest_scan_info;
+ ret = snapshot_item_scan_init(src_scan_info, src_snapshot, src_fd,
+ src_tree_id);
+ if (ret < 0) {
+ fprintf(stderr, "source snapshot scan init failed\n");
+ return ret;
+ }
+
+ ret = snapshot_item_scan_init(dest_scan_info, dest_snapshot, dest_fd,
+ dest_tree_id);
+ if (ret < 0) {
+ fprintf(stderr, "dest snapshot scan init failed\n");
+ return ret;
+ }
+
+ while (1) {
+ /*
+ * scan the specified number of items(4096) and cache
+ * them on rb-tree from both source and dest snapshot.
+ */
+ ret = snapshot_item_scan_read(src_scan_info);
+ if (ret)
+ goto out;
+
+ ret = snapshot_item_scan_read(dest_scan_info);
+ if (ret)
+ goto out;
+
+ /* fire up */
+ ret = do_diff_items(src_scan_info, dest_scan_info, flags);
+ if (ret)
+ goto out;
+
+ /*
+ * this round diff process done, free up those cached
+ * items so.
+ */
+ snapshot_item_scan_free(src_scan_info);
+ snapshot_item_scan_free(dest_scan_info);
+
+ /*
+ * no more item can be probed from the source snapshot,
+ * if the same thing happen to dest, which means that we
+ * have gone through all items in both of them, diff done.
+ * Otherwise, we''ll drop through to experience some extra
+ * check up. If there still have items at source snapshot,
+ * proceed to next round of scan && diff.
+ */
+ if (src_scan_info->scan_done) {
+ if (dest_scan_info->scan_done)
+ diff_done = 1;
+ break;
+ }
+ }
+
+ /*
+ * come to this point, probably the diff process is totally complete
+ * because of no more items can be fetched on both snapshots. or the
+ * source scan was done, and the user don''t want to list those new
+ * created items on dest snapshot, or the destination scan was done
+ * and the user don''t want to list the those items which are resides
+ * on source snapshot but may be removed on destination.
+ */
+ if (diff_done ||
+ ((src_scan_info->scan_done &&
+ !SNAPSHOT_DIFF_SHOW_NEW_ITEM(flags)) ||
+ (dest_scan_info->scan_done &&
+ !(SNAPSHOT_DIFF_SHOW_REMOVED_ITEM(flags)))))
+ goto out;
+
+ /*
+ * there may be have some items resides at either source snapshot
+ * or destination, we have to deal with them if needed.
+ */
+ if (!src_scan_info->scan_done &&
+ SNAPSHOT_DIFF_SHOW_REMOVED_ITEM(flags)) {
+ do {
+ ret = snapshot_item_scan_read(src_scan_info);
+ if (ret)
+ goto out;
+
+ ret = do_diff_items(src_scan_info, dest_scan_info,
+ flags);
+ if (ret)
+ goto out;
+ } while (!src_scan_info->scan_done);
+ }
+
+ if (!dest_scan_info->scan_done &&
+ SNAPSHOT_DIFF_SHOW_NEW_ITEM(flags)) {
+ do {
+ ret = snapshot_item_scan_read(dest_scan_info);
+ if (ret)
+ break;
+
+ ret = do_diff_items(src_scan_info, dest_scan_info,
+ flags);
+ if (ret)
+ break;
+ } while (!dest_scan_info->scan_done);
+ }
+
+out:
+ snapshot_diff_destroy(&diff_info);
+ return ret;
+}
--
1.7.4.1
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