Hi All,
the enclosed patch adds a new btrfs sub command: "btrfs inspect physical-find".
The aim of this new command is to show the physical placement on the disk of a
file. Currently it handles all the profiles (single, dup, raid1/10/5/6).
I develop this command in order to show some bug in btrfs RAID5 profile (see
next email).
You can pull the code from:
https://github.com/kreijack/btrfs-progs.git
branch
insp-phy
The syntax of this new command is simple:
# btrfs inspect physical-find <filename> [<offset>]
where:
<filename> is the file to inspect
<offset> is the offset of the file to inspect (default 0)
Below some examples:
** Single
$ sudo mkfs.btrfs -f -d single -m single /dev/loop0
$ sudo mount /dev/loop0 mnt/
$ python -c "print 'ad'+'a'*65534+'bd'+'b'*65533" | sudo tee mnt/out.txt
>/dev/null
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt
mnt/out.txt: 0
devid 1, /dev/loop0 : 12582912 LINEAR
$ dd 2>/dev/null if=/dev/loop0 skip=12582912 bs=1 count=5; echo
adaaa
** Dup
The command shows both the copies
$ sudo mkfs.btrfs -f -d single -m single /dev/loop0
$ sudo mount /dev/loop0 mnt/
$ python -c "print 'ad'+'a'*65534+'bd'+'b'*65533" | sudo tee mnt/out.txt
>/dev/null
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt
mnt/out.txt: 0
devid 1, /dev/loop0 : 71303168 DUP
devid 1, /dev/loop0 : 104857600 DUP
$ dd 2>/dev/null if=/dev/loop0 skip=104857600 bs=1 count=5 ; echo
adaaa
** Raid1
The command shows both the copies
$ sudo mkfs.btrfs -f -d raid1 -m raid1 /dev/loop0 /dev/loop1
$ sudo mount /dev/loop0 mnt/
$ python -c "print 'ad'+'a'*65534+'bd'+'b'*65533" | sudo tee mnt/out.txt
>/dev/null
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt mnt/out.txt: 0
devid 2, /dev/loop1 : 61865984 RAID1
devid 1, /dev/loop0 : 81788928 RAID1
$ dd 2>/dev/null if=/dev/loop0 skip=81788928 bs=1 count=5; echo
adaaa
** Raid10
The command show both the copies; if you set an offset to the next disk-stripe,
you can see the next pair of disk-stripe
$ sudo mkfs.btrfs -f -d raid10 -m raid10 /dev/loop[0123]
$ sudo mount /dev/loop0 mnt/
$ python -c "print 'ad'+'a'*65534+'bd'+'b'*65533" | sudo tee mnt/out.txt
>/dev/null
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt mnt/out.txt: 0
devid 4, /dev/loop3 : 61931520 RAID10
devid 3, /dev/loop2 : 61931520 RAID10
$ dd 2>/dev/null if=/dev/loop2 skip=61931520 bs=1 count=5; echo
adaaa
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt 65536
mnt/out.txt: 65536
devid 2, /dev/loop1 : 61931520 RAID10
devid 1, /dev/loop0 : 81854464 RAID10
$ dd 2>/dev/null if=/dev/loop0 skip=81854464 bs=1 count=5; echo
bdbbb
** Raid5
Depending by the offset, you can see which disk-stripe is used.
$ sudo mkfs.btrfs -f -d raid5 -m raid5 /dev/loop[012]
$ sudo mount /dev/loop0 mnt/
$ python -c "print 'ad'+'a'*65534+'bd'+'b'*65533" | sudo tee mnt/out.txt
>/dev/null
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt
mnt/out.txt: 0
devid 2, /dev/loop1 : 61931520 DATA
devid 1, /dev/loop0 : 81854464 OTHER
devid 3, /dev/loop2 : 61931520 PARITY
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt 65536mnt/out.txt:
65536
devid 2, /dev/loop1 : 61931520 OTHER
devid 1, /dev/loop0 : 81854464 DATA
devid 3, /dev/loop2 : 61931520 PARITY
$ dd 2>/dev/null if=/dev/loop1 skip=61931520 bs=1 count=5; echo
adaaa
$ dd 2>/dev/null if=/dev/loop0 skip=81854464 bs=1 count=5; echo
bdbbb
$ dd 2>/dev/null if=/dev/loop2 skip=61931520 bs=1 count=5 | xxd
00000000: 0300 0303 03 .....
The parity is computed as: parity=disk1^disk2. So "adaa" ^ "bdbb" ==
"\x03\x00\x03\x03
** Raid6
$ sudo mkfs.btrfs -f -mraid6 -draid6 /dev/loop[0-4]^C
$ sudo mount /dev/loop0 mnt/
$ python -c "print 'ad'+'a'*65534+'bd'+'b'*65533" | sudo tee mnt/out.txt
>/dev/null
$ sudo ../btrfs-progs/btrfs inspect physical-find mnt/out.txt
mnt/out.txt: 0
devid 3, /dev/loop2 : 61931520 DATA
devid 2, /dev/loop1 : 61931520 OTHER
devid 1, /dev/loop0 : 81854464 PARITY
devid 4, /dev/loop3 : 61931520 PARITY
$ dd 2>/dev/null if=/dev/loop2 skip=61931520 bs=1 count=5 ; echo
adaaa
--
diff --git a/cmds-inspect.c b/cmds-inspect.c
index dd7b9dd..a604c2b 100644
--- a/cmds-inspect.c
+++ b/cmds-inspect.c
@@ -22,6 +22,11 @@
#include <errno.h>
#include <getopt.h>
#include <limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <linux/fiemap.h>
#include "kerncompat.h"
#include "ioctl.h"
@@ -623,6 +628,450 @@ out:
return !!ret;
}
+
+static const char* const cmd_inspect_physical_find_usage[] = {
+ "btrfs inspect-internal physical-find [options] <path> [<path>...]",
+ "Show the physical address of each blocks",
+ "-m the output is machine readable",
+ NULL
+};
+
+static void dump_stripes(int ndisks, struct btrfs_ioctl_dev_info_args *disks,
+ struct btrfs_chunk *chunk, u64 logical_start) {
+ struct btrfs_stripe *stripes;
+ stripes = &chunk->stripe;
+
+ if ((chunk->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 ) {
+ /* LINEAR: each chunk has (should have) only one disk */
+ int j;
+ char *dname = "<NOT FOUND>";
+
+ assert(chunk->num_stripes == 1);
+
+ u64 phy_start = stripes[0].offset +
+ +logical_start;
+ for (j = 0 ; j < ndisks ; j++)
+ if (stripes[0].devid == disks[j].devid) {
+ dname = (char*)disks[j].path;
+ break;
+ }
+ printf("\tdevid %llu, %s : %llu LINEAR\n",
+ stripes[0].devid, dname, phy_start);
+ } else if (chunk->type & BTRFS_BLOCK_GROUP_RAID0) {
+ /*
+ * RAID0: each chunk is composed by more disks;
+ * each stripe_len bytes are in a different disk:
+ *
+ * file: ABC...NMOP....
+ *
+ * disk1 disk2 disk3 .... disksN
+ *
+ * A B C .... N
+ * M O P ....
+ *
+ */
+ u64 disks_number = chunk->num_stripes;
+ u64 disk_stripe_size = chunk->stripe_len;
+ u64 stripe_capacity ;
+ u64 stripe_nr;
+ u64 disk_stripe_start;
+ int sidx;
+ int j;
+ char *dname = "<NOT FOUND>";
+
+ stripe_capacity = disks_number * disk_stripe_size;
+ stripe_nr = logical_start / stripe_capacity;
+ disk_stripe_start = logical_start % disk_stripe_size;
+
+ sidx = (logical_start / disk_stripe_size) % disks_number;
+
+ u64 phy_start = stripes[sidx].offset +
+ stripe_nr * disk_stripe_size +
+ disk_stripe_start;
+
+ for (j = 0 ; j < ndisks ; j++)
+ if (stripes[sidx].devid == disks[j].devid) {
+ dname = (char*)disks[j].path;
+ break;
+ }
+ printf("\tdevid %llu, %s : %llu RAID0\n",
+ stripes[sidx].devid, dname, phy_start);
+
+ } else if (chunk->type & BTRFS_BLOCK_GROUP_RAID1) {
+ /*
+ * RAID0: each chunk is composed by more disks;
+ * each stripe_len bytes are in a different disk:
+ *
+ * file: ABC...
+ *
+ * disk1 disk2 disk3 ....
+ *
+ * A A
+ * B B
+ * C C
+ *
+ */
+ int sidx;
+ for (sidx = 0; sidx < chunk->num_stripes; sidx++) {
+ int j;
+ char *dname = "<NOT FOUND>";
+ u64 phy_start = stripes[sidx].offset +
+ +logical_start;
+
+ for (j = 0 ; j < ndisks ; j++)
+ if (stripes[sidx].devid == disks[j].devid) {
+ dname = (char*)disks[j].path;
+ break;
+ }
+ printf("\tdevid %llu, %s : %llu RAID1\n",
+ stripes[sidx].devid, dname, phy_start);
+ }
+ } else if (chunk->type & BTRFS_BLOCK_GROUP_DUP) {
+ /*
+ * DUP: each chunk has 'num_stripes' disk_stripe. Heach
+ * disk_stripe has its own copy of data
+ *
+ * file: ABCD....
+ *
+ * disk1 disk2 disk3
+ *
+ * A
+ * B
+ * C
+ * [...]
+ * A
+ * B
+ * C
+ *
+ *
+ * NOTE: the difference between DUP and RAID1 is that
+ * in RAID1 each disk_stripe is in a different disk, in DUP
+ * each disk chunk is in the same disk
+ */
+ int sidx;
+ /* TBD: check what happens with the stripes */
+ for (sidx = 0; sidx < chunk->num_stripes; sidx++) {
+ int j;
+ char *dname = "<NOT FOUND>";
+ u64 phy_start = stripes[sidx].offset +
+ +logical_start;
+
+ for (j = 0 ; j < ndisks ; j++)
+ if (stripes[sidx].devid == disks[j].devid) {
+ dname = (char*)disks[j].path;
+ break;
+ }
+ printf("\tdevid %llu, %s : %llu DUP\n",
+ stripes[sidx].devid, dname, phy_start);
+ }
+ } else if (chunk->type & BTRFS_BLOCK_GROUP_RAID10) {
+ /*
+ * RAID10: each chunk is composed by more disks;
+ * each stripe_len bytes are in a different disk:
+ *
+ * file: ABCD....
+ *
+ * disk1 disk2 disk3 disk4
+ *
+ * A A B B
+ * C C D D
+ *
+ *
+ */
+ int i;
+ u64 disks_number = chunk->num_stripes;
+ u64 disk_stripe_size = chunk->stripe_len;
+ u64 stripe_capacity ;
+ u64 stripe_nr;
+ u64 stripe_start;
+ u64 disk_stripe_start;
+
+ stripe_capacity = disks_number * disk_stripe_size /
chunk->sub_stripes;
+ stripe_nr = logical_start / stripe_capacity;
+ stripe_start = logical_start % stripe_capacity;
+ disk_stripe_start = logical_start % disk_stripe_size;
+
+ for (i = 0; i < chunk->sub_stripes; i++) {
+ int j;
+ char *dname = "<NOT FOUND>";
+ int sidx = (i +
+ stripe_start/disk_stripe_size*chunk->sub_stripes) %
+ disks_number;
+
+ u64 phy_start = stripes[sidx].offset +
+ +stripe_nr*disk_stripe_size +
disk_stripe_start;
+
+ for (j = 0 ; j < ndisks ; j++)
+ if (stripes[sidx].devid == disks[j].devid) {
+ dname = (char*)disks[j].path;
+ break;
+ }
+ printf("\tdevid %llu, %s : %llu RAID10\n",
+ stripes[sidx].devid, dname, phy_start);
+ }
+ } else if (chunk->type & BTRFS_BLOCK_GROUP_RAID5 ||
+ chunk->type & BTRFS_BLOCK_GROUP_RAID6 ) {
+ /*
+ * RAID5: each chunk is spread on a different disk; however one
+ * disk is used for parity
+ *
+ * file: ABCDEFGHIJK....
+ *
+ * disk1 disk2 disk3 disk4 disk5
+ *
+ * A B C D P
+ * P D E F G
+ * H P I J K
+ *
+ * Note: P == parity
+ *
+ * RAID6: each chunk is spread on a different disk; however two
+ * disks are used for parity
+ *
+ * file: ABCDEFGHI...
+ *
+ * disk1 disk2 disk3 disk4 disk5
+ *
+ * A B C P Q
+ * Q D E F P
+ * P Q G H I
+ *
+ * Note: P,Q == parity
+ *
+ */
+ int parities_nr = 1;
+ u64 disks_number = chunk->num_stripes;
+ u64 disk_stripe_size = chunk->stripe_len;
+ u64 stripe_capacity ;
+ u64 stripe_nr;
+ u64 stripe_start;
+ u64 pos = 0;
+ u64 disk_stripe_start;
+ int sidx;
+
+ if (chunk->type & BTRFS_BLOCK_GROUP_RAID6)
+ parities_nr = 2;
+
+ stripe_capacity = (disks_number - parities_nr) *
+ disk_stripe_size;
+ stripe_nr = logical_start / stripe_capacity;
+ stripe_start = logical_start % stripe_capacity;
+ disk_stripe_start = logical_start % disk_stripe_size;
+
+ for (sidx = 0; sidx < disks_number ; sidx++) {
+ int j;
+ char *dname = "<NOT FOUND>";
+ u64 stripe_index = (sidx + stripe_nr) % disks_number;
+ u64 phy_start = stripes[stripe_index].offset + /*
chunk start */
+ + stripe_nr*disk_stripe_size + /* stripe
start */
+ + disk_stripe_start;
+
+ for (j = 0 ; j < ndisks ; j++)
+ if (stripes[stripe_index].devid == disks[j].devid)
{
+ dname = (char*)disks[j].path;
+ break;
+ }
+
+ if (sidx >= (disks_number - parities_nr)) {
+ printf("\tdevid %llu, %s : %llu PARITY\n",
+ stripes[stripe_index].devid, dname,
+ phy_start);
+ continue;
+ }
+
+ if (stripe_start >= pos && stripe_start <
(pos+disk_stripe_size)) {
+ printf("\tdevid %llu, %s : %llu DATA\n",
+ stripes[stripe_index].devid,
+ dname, phy_start);
+ } else {
+ printf("\tdevid %llu, %s : %llu OTHER\n",
+ stripes[stripe_index].devid,
+ dname, phy_start);
+ }
+
+ pos += disk_stripe_size;
+ }
+ assert(pos == stripe_capacity);
+ } else {
+ error("Unknown chunk type = 0x%016llx\n", chunk->type);
+ return;
+ }
+
+}
+
+static int dump_extent(char *fname, int fd, u64 logical_start) {
+
+ struct btrfs_ioctl_search_args args;
+ struct btrfs_ioctl_search_key *sk = &args.key;
+ struct btrfs_ioctl_search_header sh;
+ unsigned long off = 0;
+ int i;
+ int e;
+ struct btrfs_ioctl_dev_info_args *disks = NULL;
+ struct btrfs_ioctl_fs_info_args fi_args = {0};
+
+ e = get_fs_info(fname, &fi_args, &disks);
+ if ( e< 0) {
+ error("Cannot get info for the filesystem: may be it is not a
btrfs filesystem ?\n");
+ free(disks);
+ return -1;
+ }
+
+ memset(&args, 0, sizeof(args));
+ sk->tree_id = BTRFS_CHUNK_TREE_OBJECTID;
+ sk->min_objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+ sk->max_objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+ sk->min_type = BTRFS_CHUNK_ITEM_KEY;
+ sk->max_type = BTRFS_CHUNK_ITEM_KEY;
+ sk->max_offset = (u64)-1;
+ sk->min_offset = 0;
+ sk->max_transid = (u64)-1;
+
+ while (1) {
+ int ret;
+
+ sk->nr_items = 1;
+ ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
+ e = errno;
+ if (ret < 0) {
+ error("cannot perform the search: %s", strerror(e));
+ free(disks);
+ return -1;
+ }
+ if (sk->nr_items == 0)
+ break;
+
+ off = 0;
+ for (i = 0; i < sk->nr_items; i++) {
+ struct btrfs_chunk *item;
+
+ memcpy(&sh, args.buf + off, sizeof(sh));
+ off += sizeof(sh);
+ item = (struct btrfs_chunk*)(args.buf + off);
+ off += sh.len;
+
+ if (logical_start >= sh.offset &&
+ logical_start <= sh.offset+item->length) {
+ dump_stripes(fi_args.num_devices,
disks,
+ item,
+ logical_start-sh.offset);
+ free(disks);
+ return 0;
+ }
+
+
+ sk->min_objectid = sh.objectid;
+ sk->min_type = sh.type;
+ sk->min_offset = sh.offset;
+ }
+
+ if (sk->min_offset < (u64)-1)
+ sk->min_offset++;
+ else
+ break;
+ }
+
+ free(disks);
+ return 0;
+}
+
+/*
+ * Inline extents are skipped because they do not take data space,
+ * delalloc and unknown are skipped because we do not know how much
+ * space they will use yet.
+ */
+#define SKIP_FLAGS (FIEMAP_EXTENT_UNKNOWN|FIEMAP_EXTENT_DELALLOC| \
+ FIEMAP_EXTENT_DATA_INLINE)
+static int cmd_inspect_physical_find(int argc, char **argv)
+{
+ int ret = 0;
+ u64 logical = 0ull;
+ int fd;
+ int last = 0;
+ char buf[16384];
+ char *fname;
+ int found = 0;
+ struct fiemap *fiemap = (struct fiemap*)buf;
+ struct fiemap_extent *fm_ext = &fiemap->fm_extents[0];
+ const int count = (sizeof(buf) - sizeof(*fiemap)) /
+ sizeof(struct fiemap_extent);
+
+ int minargc = 1;
+
+ memset(fiemap, 0, sizeof(struct fiemap));
+
+ if (check_argc_min(argc - minargc, 1) ||
+ check_argc_max(argc - minargc, 2) )
+ usage(cmd_inspect_physical_find_usage);
+
+ if (argc - minargc == 2)
+ logical = strtoull(argv[minargc+1], NULL, 0);
+ fname = argv[minargc];
+
+ printf("%s: %llu\n", fname, logical);
+
+ fd = open(fname, O_RDONLY);
+ if (fd < 0) {
+ error("Can't open '%s' for reading\n", fname);
+ ret = -errno;
+ goto out;
+ }
+
+ do {
+
+ int rc;
+ int j;
+
+ fiemap->fm_length = ~0ULL;
+ fiemap->fm_extent_count = count;
+ fiemap->fm_flags = FIEMAP_FLAG_SYNC;
+ rc = ioctl(fd, FS_IOC_FIEMAP, (unsigned long) fiemap);
+ if (rc < 0) {
+ error("Can't do ioctl()\n");
+ close(fd);
+ ret = -errno;
+ goto out;
+ }
+
+ for (j = 0; j < fiemap->fm_mapped_extents; j++) {
+ u32 flags = fm_ext[j].fe_flags;
+
+ fiemap->fm_start = (fm_ext[j].fe_logical +
+ fm_ext[j].fe_length);
+
+ if (flags & FIEMAP_EXTENT_LAST)
+ last = 1;
+
+ if (flags & SKIP_FLAGS)
+ continue;
+
+ if (logical > fm_ext[j].fe_logical +
+ fm_ext[j].fe_length)
+ continue;
+
+ found = 1;
+
+ rc = dump_extent(fname, fd,
+ fm_ext[j].fe_physical + logical -
+ fm_ext[j].fe_logical);
+ if (rc < 0)
+ ret = -errno;
+ last = 1;
+ break;
+ }
+ } while (last == 0);
+
+ close(fd);
+
+ if (!found) {
+ error("Can't find the extent: the file is too short, or the file
is stored in a leaf.\n");
+ ret = 10;
+ }
+
+out:
+ return ret;
+}
+
static const char inspect_cmd_group_info[] =
"query various internal information";
@@ -644,6 +1093,8 @@ const struct cmd_group inspect_cmd_group = {
cmd_inspect_dump_super_usage, NULL, 0 },
{ "tree-stats", cmd_inspect_tree_stats,
cmd_inspect_tree_stats_usage, NULL, 0 },
+ { "physical-find", cmd_inspect_physical_find,
+ cmd_inspect_physical_find_usage, NULL, 0 },
NULL_CMD_STRUCT
}
};
--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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