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dm integrity: add recovery mode 

In recovery mode, we don't:
- replay the journal
- check checksums
- allow writes to the device

This mode can be used as a last resort for data recovery.  The
motivation for recovery mode is that when there is a single error in the
journal, the user should not lose access to the whole device.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2017-03-17 12:40:51 -04:00 committed by Mike Snitzer
parent 1aa0efd421
commit c2bcb2b702
2 changed files with 32 additions and 13 deletions
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5
Documentation/device-mapper/dm-integrity.txt
View File

@ -59,6 +59,11 @@ Target arguments:
either both data and tag or none of them are written. The
journaled mode degrades write throughput twice because the
data have to be written twice.
R - recovery mode - in this mode, journal is not replayed,
checksums are not checked and writes to the device are not
allowed. This mode is useful for data recovery if the
device cannot be activated in any of the other standard
modes.
5. the number of additional arguments

40
drivers/md/dm-integrity.c
View File

@ -1216,6 +1216,9 @@ static void integrity_metadata(struct work_struct *w)
unsigned sectors_to_process = dio->range.n_sectors;
sector_t sector = dio->range.logical_sector;
if (unlikely(ic->mode == 'R'))
goto skip_io;
checksums = kmalloc((PAGE_SIZE >> SECTOR_SHIFT) * ic->tag_size + extra_space,
GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
if (!checksums)
@ -1288,6 +1291,7 @@ again:
}
}
}
skip_io:
dec_in_flight(dio);
return;
error:
@ -1327,6 +1331,9 @@ static int dm_integrity_map(struct dm_target *ti, struct bio *bio)
return -EIO;
}
if (unlikely(ic->mode == 'R') && unlikely(dio->write))
return -EIO;
get_area_and_offset(ic, dio->range.logical_sector, &area, &offset);
dio->metadata_block = get_metadata_sector_and_offset(ic, area, offset, &dio->metadata_offset);
bio->bi_iter.bi_sector = get_data_sector(ic, area, offset);
@ -1926,6 +1933,9 @@ static void replay_journal(struct dm_integrity_c *ic)
bool journal_empty;
unsigned char unused, last_used, want_commit_seq;
if (ic->mode == 'R')
return;
if (ic->journal_uptodate)
return;
@ -2705,7 +2715,7 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
}
}
if (!strcmp(argv[3], "J") || !strcmp(argv[3], "D"))
if (!strcmp(argv[3], "J") || !strcmp(argv[3], "D") || !strcmp(argv[3], "R"))
ic->mode = argv[3][0];
else {
ti->error = "Invalid mode (expecting J or D)";
@ -2864,14 +2874,15 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
ti->error = "Error reading superblock";
goto bad;
}
if (!memcmp(ic->sb->magic, SB_MAGIC, 8)) {
should_write_sb = false;
} else {
for (i = 0; i < 512; i += 8) {
if (*(__u64 *)((__u8 *)ic->sb + i)) {
r = -EINVAL;
ti->error = "The device is not initialized";
goto bad;
should_write_sb = false;
if (memcmp(ic->sb->magic, SB_MAGIC, 8)) {
if (ic->mode != 'R') {
for (i = 0; i < 512; i += 8) {
if (*(__u64 *)((__u8 *)ic->sb + i)) {
r = -EINVAL;
ti->error = "The device is not initialized";
goto bad;
}
}
}
@ -2880,7 +2891,8 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
ti->error = "Could not initialize superblock";
goto bad;
}
should_write_sb = true;
if (ic->mode != 'R')
should_write_sb = true;
}
if (ic->sb->version != SB_VERSION) {
@ -2954,9 +2966,11 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
}
dm_bufio_set_sector_offset(ic->bufio, ic->start + ic->initial_sectors);
r = create_journal(ic, &ti->error);
if (r)
goto bad;
if (ic->mode != 'R') {
r = create_journal(ic, &ti->error);
if (r)
goto bad;
}
if (should_write_sb) {
int r;