Wang Shilong
2014-May-28 11:22 UTC
[PATCH v2] Btrfs-progs: fsck: add an option to check data csums
This patch adds an option '--check-data-csum' to verify data checksums.
fsck won't check data csums unless users specify this option explictly.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
---
v1->v2:
addressed comments from david.
read as much as data once a time.
---
Documentation/btrfs-check.txt | 2 +
cmds-check.c | 125 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 123 insertions(+), 4 deletions(-)
diff --git a/Documentation/btrfs-check.txt b/Documentation/btrfs-check.txt
index 485a49c..4623659 100644
--- a/Documentation/btrfs-check.txt
+++ b/Documentation/btrfs-check.txt
@@ -30,6 +30,8 @@ try to repair the filesystem.
create a new CRC tree.
--init-extent-tree::
create a new extent tree.
+--check-data-csum::
+verify checkums of data blocks.
EXIT STATUS
-----------
diff --git a/cmds-check.c b/cmds-check.c
index 55e7753..058956e 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -54,6 +54,7 @@ static LIST_HEAD(delete_items);
static int repair = 0;
static int no_holes = 0;
static int init_extent_tree = 0;
+static int check_data_csum = 0;
struct extent_backref {
struct list_head list;
@@ -3733,6 +3734,109 @@ static int check_space_cache(struct btrfs_root *root)
return error ? -EINVAL : 0;
}
+static int read_extent_data(struct btrfs_root *root, char *data,
+ u64 logical, u64 *len, int mirror)
+{
+ u64 offset = 0;
+ struct btrfs_multi_bio *multi = NULL;
+ struct btrfs_fs_info *info = root->fs_info;
+ struct btrfs_device *device;
+ int ret = 0;
+ u64 max_len = *len;
+
+ ret = btrfs_map_block(&info->mapping_tree, READ, logical, len,
+ &multi, mirror, NULL);
+ if (ret) {
+ fprintf(stderr, "Couldn't map the block %llu\n",
+ logical + offset);
+ goto err;
+ }
+ device = multi->stripes[0].dev;
+
+ if (device->fd == 0)
+ goto err;
+ if (*len > max_len)
+ *len = max_len;
+
+ ret = pread64(device->fd, data, *len, multi->stripes[0].physical);
+ if (ret != *len)
+ ret = -EIO;
+ else
+ ret = 0;
+err:
+ kfree(multi);
+ return ret;
+}
+
+static int check_extent_csums(struct btrfs_root *root, u64 bytenr,
+ u64 num_bytes, unsigned long leaf_offset,
+ struct extent_buffer *eb) {
+
+ u64 offset = 0;
+ u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
+ char *data;
+ unsigned long csum_offset;
+ u32 csum;
+ u32 csum_expected;
+ u64 read_len;
+ u64 data_checked = 0;
+ u64 tmp;
+ int ret = 0;
+ int mirror;
+ int num_copies;
+
+ if (num_bytes % root->sectorsize)
+ return -EINVAL;
+
+ data = malloc(num_bytes);
+ if (!data)
+ return -ENOMEM;
+
+ while (offset < num_bytes) {
+ mirror = 0;
+again:
+ read_len = num_bytes - offset;
+ /* read as much space once a time */
+ ret = read_extent_data(root, data + offset,
+ bytenr + offset, &read_len, mirror);
+ if (ret)
+ goto out;
+ data_checked = 0;
+ /* verify every 4k data's checksum */
+ while (data_checked < read_len) {
+ csum = ~(u32)0;
+ tmp = offset + data_checked;
+
+ csum = btrfs_csum_data(NULL, (char *)data + tmp,
+ csum, root->sectorsize);
+ btrfs_csum_final(csum, (char *)&csum);
+
+ csum_offset = leaf_offset +
+ tmp / root->sectorsize * csum_size;
+ read_extent_buffer(eb, (char *)&csum_expected,
+ csum_offset, csum_size);
+ /* try another mirror */
+ if (csum != csum_expected) {
+ fprintf(stderr, "mirror %d bytenr %llu csum %u expected csum
%u\n",
+ mirror, bytenr + tmp,
+ csum, csum_expected);
+ num_copies = btrfs_num_copies(
+ &root->fs_info->mapping_tree,
+ bytenr, num_bytes);
+ if (mirror < num_copies - 1) {
+ mirror += 1;
+ goto again;
+ }
+ }
+ data_checked += root->sectorsize;
+ }
+ offset += read_len;
+ }
+out:
+ free(data);
+ return ret;
+}
+
static int check_extent_exists(struct btrfs_root *root, u64 bytenr,
u64 num_bytes)
{
@@ -3886,6 +3990,8 @@ static int check_csums(struct btrfs_root *root)
u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
int errors = 0;
int ret;
+ u64 data_len;
+ unsigned long leaf_offset;
root = root->fs_info->csum_root;
@@ -3927,6 +4033,16 @@ static int check_csums(struct btrfs_root *root)
continue;
}
+ data_len = (btrfs_item_size_nr(leaf, path->slots[0]) /
+ csum_size) * root->sectorsize;
+ if (!check_data_csum)
+ goto skip_csum_check;
+ leaf_offset = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ ret = check_extent_csums(root, key.offset, data_len,
+ leaf_offset, leaf);
+ if (ret)
+ break;
+skip_csum_check:
if (!num_bytes) {
offset = key.offset;
} else if (key.offset != offset + num_bytes) {
@@ -3940,9 +4056,7 @@ static int check_csums(struct btrfs_root *root)
offset = key.offset;
num_bytes = 0;
}
-
- num_bytes += (btrfs_item_size_nr(leaf, path->slots[0]) /
- csum_size) * root->sectorsize;
+ num_bytes += data_len;
path->slots[0]++;
}
@@ -6780,6 +6894,7 @@ static struct option long_options[] = {
{ "repair", 0, NULL, 0 },
{ "init-csum-tree", 0, NULL, 0 },
{ "init-extent-tree", 0, NULL, 0 },
+ { "check-data-csum", 0, NULL, 0 },
{ "backup", 0, NULL, 0 },
{ "qgroup-report", 0, NULL, 'Q' },
{ NULL, 0, NULL, 0}
@@ -6794,6 +6909,7 @@ const char * const cmd_check_usage[] = {
"--repair try to repair the filesystem",
"--init-csum-tree create a new CRC tree",
"--init-extent-tree create a new extent tree",
+ "--check-data-csum verify checkums of data blocks",
"--qgroup-report print a report on qgroup consistency",
NULL
};
@@ -6856,8 +6972,9 @@ int cmd_check(int argc, char **argv)
ctree_flags |= (OPEN_CTREE_WRITES |
OPEN_CTREE_NO_BLOCK_GROUPS);
repair = 1;
+ } else if (option_index == 4) {
+ check_data_csum = 1;
}
-
}
argc = argc - optind;
--
1.9.0
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