btrfs: scrub: fix subpage repair error caused by hard coded PAGE_SIZE

[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>

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 5839ad1..b60466d 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -631,7 +631,6 @@ nomem:
 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
                                     void *warn_ctx)
 {
-       u64 isize;
        u32 nlink;
        int ret;
        int i;
@@ -667,7 +666,6 @@ 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);
 
@@ -696,12 +694,12 @@ 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);
@@ -890,25 +888,25 @@ 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
@@ -1065,26 +1063,26 @@ 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;
@@ -1265,7 +1263,7 @@ 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;
@@ -1288,13 +1286,13 @@ 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,
@@ -1485,7 +1483,7 @@ 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;
 
@@ -1549,6 +1547,7 @@ 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);
@@ -1568,8 +1567,8 @@ 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;
                }
@@ -1647,6 +1646,7 @@ 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:
@@ -1686,16 +1686,16 @@ again:
                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;
@@ -1734,7 +1734,8 @@ 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)
@@ -2072,6 +2073,7 @@ 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:
@@ -2110,9 +2112,9 @@ again:
                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);
@@ -2120,8 +2122,8 @@ again:
        }
 
        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;
@@ -2464,7 +2466,7 @@ 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,