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Subject[PATCH AUTOSEL 5.13 74/85] btrfs: scrub: fix subpage repair error caused by hard coded PAGE_SIZE
Date
From: Qu Wenruo <wqu@suse.com>

[ Upstream commit 8df507cbb5952719353c912a021b66c27641e90c ]

[BUG]
For the following file layout, scrub will not be able to repair all
these two repairable error, but in fact make one corruption even
unrepairable:

inode offset 0 4k 8K
Mirror 1 |XXXXXX| |
Mirror 2 | |XXXXXX|

[CAUSE]
The root cause is the hard coded PAGE_SIZE, which makes scrub repair to
go crazy for subpage.

For above case, when reading the first sector, we use PAGE_SIZE other
than sectorsize to read, which makes us to read the full range [0, 64K).
In fact, after 8K there may be no data at all, we can just get some
garbage.

Then when doing the repair, we also writeback a full page from mirror 2,
this means, we will also writeback the corrupted data in mirror 2 back
to mirror 1, leaving the range [4K, 8K) unrepairable.

[FIX]
This patch will modify the following PAGE_SIZE use with sectorsize:

- scrub_print_warning_inode()
Remove the min() and replace PAGE_SIZE with sectorsize.
The min() makes no sense, as csum is done for the full sector with
padding.

This fixes a bug that subpage report extra length like:
checksum error at logical 298844160 on dev /dev/mapper/arm_nvme-test,
physical 575668224, root 5, inode 257, offset 0, length 12288, links 1 (path: file)

Where the error is only 1 sector.

- scrub_handle_errored_block()
Comments with PAGE|page involved, all changed to sector.

- scrub_setup_recheck_block()
- scrub_repair_page_from_good_copy()
- scrub_add_page_to_wr_bio()
- scrub_wr_submit()
- scrub_add_page_to_rd_bio()
- scrub_block_complete()
Replace PAGE_SIZE with sectorsize.
This solves several problems where we read/write extra range for
subpage case.

RAID56 code is excluded intentionally, as RAID56 has extra PAGE_SIZE
usage, and is not really safe enough.
Thus we will reject RAID56 for subpage in later commit.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/scrub.c | 82 +++++++++++++++++++++++++-----------------------
1 file changed, 42 insertions(+), 40 deletions(-)

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 485cda3eb8d7..6af901539ef2 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -626,7 +626,6 @@ static noinline_for_stack struct scrub_ctx *scrub_setup_ctx(
static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
void *warn_ctx)
{
- u64 isize;
u32 nlink;
int ret;
int i;
@@ -662,7 +661,6 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
eb = swarn->path->nodes[0];
inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
struct btrfs_inode_item);
- isize = btrfs_inode_size(eb, inode_item);
nlink = btrfs_inode_nlink(eb, inode_item);
btrfs_release_path(swarn->path);

@@ -691,12 +689,12 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
*/
for (i = 0; i < ipath->fspath->elem_cnt; ++i)
btrfs_warn_in_rcu(fs_info,
-"%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu, length %llu, links %u (path: %s)",
+"%s at logical %llu on dev %s, physical %llu, root %llu, inode %llu, offset %llu, length %u, links %u (path: %s)",
swarn->errstr, swarn->logical,
rcu_str_deref(swarn->dev->name),
swarn->physical,
root, inum, offset,
- min(isize - offset, (u64)PAGE_SIZE), nlink,
+ fs_info->sectorsize, nlink,
(char *)(unsigned long)ipath->fspath->val[i]);

btrfs_put_root(local_root);
@@ -885,25 +883,25 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
* read all mirrors one after the other. This includes to
* re-read the extent or metadata block that failed (that was
* the cause that this fixup code is called) another time,
- * page by page this time in order to know which pages
+ * sector by sector this time in order to know which sectors
* caused I/O errors and which ones are good (for all mirrors).
* It is the goal to handle the situation when more than one
* mirror contains I/O errors, but the errors do not
* overlap, i.e. the data can be repaired by selecting the
- * pages from those mirrors without I/O error on the
- * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
- * would be that mirror #1 has an I/O error on the first page,
- * the second page is good, and mirror #2 has an I/O error on
- * the second page, but the first page is good.
- * Then the first page of the first mirror can be repaired by
- * taking the first page of the second mirror, and the
- * second page of the second mirror can be repaired by
- * copying the contents of the 2nd page of the 1st mirror.
- * One more note: if the pages of one mirror contain I/O
+ * sectors from those mirrors without I/O error on the
+ * particular sectors. One example (with blocks >= 2 * sectorsize)
+ * would be that mirror #1 has an I/O error on the first sector,
+ * the second sector is good, and mirror #2 has an I/O error on
+ * the second sector, but the first sector is good.
+ * Then the first sector of the first mirror can be repaired by
+ * taking the first sector of the second mirror, and the
+ * second sector of the second mirror can be repaired by
+ * copying the contents of the 2nd sector of the 1st mirror.
+ * One more note: if the sectors of one mirror contain I/O
* errors, the checksum cannot be verified. In order to get
* the best data for repairing, the first attempt is to find
* a mirror without I/O errors and with a validated checksum.
- * Only if this is not possible, the pages are picked from
+ * Only if this is not possible, the sectors are picked from
* mirrors with I/O errors without considering the checksum.
* If the latter is the case, at the end, the checksum of the
* repaired area is verified in order to correctly maintain
@@ -1060,26 +1058,26 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)

/*
* In case of I/O errors in the area that is supposed to be
- * repaired, continue by picking good copies of those pages.
- * Select the good pages from mirrors to rewrite bad pages from
+ * repaired, continue by picking good copies of those sectors.
+ * Select the good sectors from mirrors to rewrite bad sectors from
* the area to fix. Afterwards verify the checksum of the block
* that is supposed to be repaired. This verification step is
* only done for the purpose of statistic counting and for the
* final scrub report, whether errors remain.
* A perfect algorithm could make use of the checksum and try
- * all possible combinations of pages from the different mirrors
+ * all possible combinations of sectors from the different mirrors
* until the checksum verification succeeds. For example, when
- * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
+ * the 2nd sector of mirror #1 faces I/O errors, and the 2nd sector
* of mirror #2 is readable but the final checksum test fails,
- * then the 2nd page of mirror #3 could be tried, whether now
+ * then the 2nd sector of mirror #3 could be tried, whether now
* the final checksum succeeds. But this would be a rare
* exception and is therefore not implemented. At least it is
* avoided that the good copy is overwritten.
* A more useful improvement would be to pick the sectors
* without I/O error based on sector sizes (512 bytes on legacy
- * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
+ * disks) instead of on sectorsize. Then maybe 512 byte of one
* mirror could be repaired by taking 512 byte of a different
- * mirror, even if other 512 byte sectors in the same PAGE_SIZE
+ * mirror, even if other 512 byte sectors in the same sectorsize
* area are unreadable.
*/
success = 1;
@@ -1260,7 +1258,7 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
{
struct scrub_ctx *sctx = original_sblock->sctx;
struct btrfs_fs_info *fs_info = sctx->fs_info;
- u64 length = original_sblock->page_count * PAGE_SIZE;
+ u64 length = original_sblock->page_count * fs_info->sectorsize;
u64 logical = original_sblock->pagev[0]->logical;
u64 generation = original_sblock->pagev[0]->generation;
u64 flags = original_sblock->pagev[0]->flags;
@@ -1283,13 +1281,13 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
*/

while (length > 0) {
- sublen = min_t(u64, length, PAGE_SIZE);
+ sublen = min_t(u64, length, fs_info->sectorsize);
mapped_length = sublen;
bbio = NULL;

/*
- * with a length of PAGE_SIZE, each returned stripe
- * represents one mirror
+ * With a length of sectorsize, each returned stripe represents
+ * one mirror
*/
btrfs_bio_counter_inc_blocked(fs_info);
ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
@@ -1480,7 +1478,7 @@ static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
bio = btrfs_io_bio_alloc(1);
bio_set_dev(bio, spage->dev->bdev);

- bio_add_page(bio, spage->page, PAGE_SIZE, 0);
+ bio_add_page(bio, spage->page, fs_info->sectorsize, 0);
bio->bi_iter.bi_sector = spage->physical >> 9;
bio->bi_opf = REQ_OP_READ;

@@ -1544,6 +1542,7 @@ static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
struct scrub_page *spage_bad = sblock_bad->pagev[page_num];
struct scrub_page *spage_good = sblock_good->pagev[page_num];
struct btrfs_fs_info *fs_info = sblock_bad->sctx->fs_info;
+ const u32 sectorsize = fs_info->sectorsize;

BUG_ON(spage_bad->page == NULL);
BUG_ON(spage_good->page == NULL);
@@ -1563,8 +1562,8 @@ static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
bio->bi_iter.bi_sector = spage_bad->physical >> 9;
bio->bi_opf = REQ_OP_WRITE;

- ret = bio_add_page(bio, spage_good->page, PAGE_SIZE, 0);
- if (PAGE_SIZE != ret) {
+ ret = bio_add_page(bio, spage_good->page, sectorsize, 0);
+ if (ret != sectorsize) {
bio_put(bio);
return -EIO;
}
@@ -1642,6 +1641,7 @@ static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
{
struct scrub_bio *sbio;
int ret;
+ const u32 sectorsize = sctx->fs_info->sectorsize;

mutex_lock(&sctx->wr_lock);
again:
@@ -1681,16 +1681,16 @@ static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
bio->bi_iter.bi_sector = sbio->physical >> 9;
bio->bi_opf = REQ_OP_WRITE;
sbio->status = 0;
- } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
+ } else if (sbio->physical + sbio->page_count * sectorsize !=
spage->physical_for_dev_replace ||
- sbio->logical + sbio->page_count * PAGE_SIZE !=
+ sbio->logical + sbio->page_count * sectorsize !=
spage->logical) {
scrub_wr_submit(sctx);
goto again;
}

- ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
- if (ret != PAGE_SIZE) {
+ ret = bio_add_page(sbio->bio, spage->page, sectorsize, 0);
+ if (ret != sectorsize) {
if (sbio->page_count < 1) {
bio_put(sbio->bio);
sbio->bio = NULL;
@@ -1729,7 +1729,8 @@ static void scrub_wr_submit(struct scrub_ctx *sctx)
btrfsic_submit_bio(sbio->bio);

if (btrfs_is_zoned(sctx->fs_info))
- sctx->write_pointer = sbio->physical + sbio->page_count * PAGE_SIZE;
+ sctx->write_pointer = sbio->physical + sbio->page_count *
+ sctx->fs_info->sectorsize;
}

static void scrub_wr_bio_end_io(struct bio *bio)
@@ -2006,6 +2007,7 @@ static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
{
struct scrub_block *sblock = spage->sblock;
struct scrub_bio *sbio;
+ const u32 sectorsize = sctx->fs_info->sectorsize;
int ret;

again:
@@ -2044,9 +2046,9 @@ static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
bio->bi_iter.bi_sector = sbio->physical >> 9;
bio->bi_opf = REQ_OP_READ;
sbio->status = 0;
- } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
+ } else if (sbio->physical + sbio->page_count * sectorsize !=
spage->physical ||
- sbio->logical + sbio->page_count * PAGE_SIZE !=
+ sbio->logical + sbio->page_count * sectorsize !=
spage->logical ||
sbio->dev != spage->dev) {
scrub_submit(sctx);
@@ -2054,8 +2056,8 @@ static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
}

sbio->pagev[sbio->page_count] = spage;
- ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
- if (ret != PAGE_SIZE) {
+ ret = bio_add_page(sbio->bio, spage->page, sectorsize, 0);
+ if (ret != sectorsize) {
if (sbio->page_count < 1) {
bio_put(sbio->bio);
sbio->bio = NULL;
@@ -2398,7 +2400,7 @@ static void scrub_block_complete(struct scrub_block *sblock)
if (sblock->sparity && corrupted && !sblock->data_corrected) {
u64 start = sblock->pagev[0]->logical;
u64 end = sblock->pagev[sblock->page_count - 1]->logical +
- PAGE_SIZE;
+ sblock->sctx->fs_info->sectorsize;

ASSERT(end - start <= U32_MAX);
scrub_parity_mark_sectors_error(sblock->sparity,
--
2.30.2
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