btrfs: zoned: fix parallel compressed writes

When multiple processes write data to the same block group on a
compressed zoned filesystem, the underlying device could report I/O
errors and data corruption is possible.

This happens because on a zoned file system, compressed data writes
where sent to the device via a REQ_OP_WRITE instead of a
REQ_OP_ZONE_APPEND operation. But with REQ_OP_WRITE and parallel
submission it cannot be guaranteed that the data is always submitted
aligned to the underlying zone's write pointer.

The change to using REQ_OP_ZONE_APPEND instead of REQ_OP_WRITE on a
zoned filesystem is non intrusive on a regular file system or when
submitting to a conventional zone on a zoned filesystem, as it is
guarded by btrfs_use_zone_append.

Reported-by: David Sterba <dsterba@suse.com>
Fixes: 9d294a685fbc ("btrfs: zoned: enable to mount ZONED incompat flag")
CC: stable@vger.kernel.org # 5.12.x: e380adfc213a13: btrfs: zoned: pass start block to btrfs_use_zone_append
CC: stable@vger.kernel.org # 5.12.x
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 17f93fd..91743a0 100644 (file)
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -28,6 +28,7 @@
 #include "compression.h"
 #include "extent_io.h"
 #include "extent_map.h"
+#include "zoned.h"
 
 static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" };
 
@@ -349,6 +350,7 @@ static void end_compressed_bio_write(struct bio *bio)
         */
        inode = cb->inode;
        cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
+       btrfs_record_physical_zoned(inode, cb->start, bio);
        btrfs_writepage_endio_finish_ordered(cb->compressed_pages[0],
                        cb->start, cb->start + cb->len - 1,
                        bio->bi_status == BLK_STS_OK);
@@ -401,6 +403,8 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
        u64 first_byte = disk_start;
        blk_status_t ret;
        int skip_sum = inode->flags & BTRFS_INODE_NODATASUM;
+       const bool use_append = btrfs_use_zone_append(inode, disk_start);
+       const unsigned int bio_op = use_append ? REQ_OP_ZONE_APPEND : REQ_OP_WRITE;
 
        WARN_ON(!PAGE_ALIGNED(start));
        cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
@@ -418,10 +422,31 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
        cb->nr_pages = nr_pages;
 
        bio = btrfs_bio_alloc(first_byte);
-       bio->bi_opf = REQ_OP_WRITE | write_flags;
+       bio->bi_opf = bio_op | write_flags;
        bio->bi_private = cb;
        bio->bi_end_io = end_compressed_bio_write;
 
+       if (use_append) {
+               struct extent_map *em;
+               struct map_lookup *map;
+               struct block_device *bdev;
+
+               em = btrfs_get_chunk_map(fs_info, disk_start, PAGE_SIZE);
+               if (IS_ERR(em)) {
+                       kfree(cb);
+                       bio_put(bio);
+                       return BLK_STS_NOTSUPP;
+               }
+
+               map = em->map_lookup;
+               /* We only support single profile for now */
+               ASSERT(map->num_stripes == 1);
+               bdev = map->stripes[0].dev->bdev;
+
+               bio_set_dev(bio, bdev);
+               free_extent_map(em);
+       }
+
        if (blkcg_css) {
                bio->bi_opf |= REQ_CGROUP_PUNT;
                kthread_associate_blkcg(blkcg_css);
@@ -432,6 +457,7 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
        bytes_left = compressed_len;
        for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
                int submit = 0;
+               int len;
 
                page = compressed_pages[pg_index];
                page->mapping = inode->vfs_inode.i_mapping;
@@ -439,9 +465,13 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
                        submit = btrfs_bio_fits_in_stripe(page, PAGE_SIZE, bio,
                                                          0);
 
+               if (pg_index == 0 && use_append)
+                       len = bio_add_zone_append_page(bio, page, PAGE_SIZE, 0);
+               else
+                       len = bio_add_page(bio, page, PAGE_SIZE, 0);
+
                page->mapping = NULL;
-               if (submit || bio_add_page(bio, page, PAGE_SIZE, 0) <
-                   PAGE_SIZE) {
+               if (submit || len < PAGE_SIZE) {
                        /*
                         * inc the count before we submit the bio so
                         * we know the end IO handler won't happen before
@@ -465,11 +495,15 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
                        }
 
                        bio = btrfs_bio_alloc(first_byte);
-                       bio->bi_opf = REQ_OP_WRITE | write_flags;
+                       bio->bi_opf = bio_op | write_flags;
                        bio->bi_private = cb;
                        bio->bi_end_io = end_compressed_bio_write;
                        if (blkcg_css)
                                bio->bi_opf |= REQ_CGROUP_PUNT;
+                       /*
+                        * Use bio_add_page() to ensure the bio has at least one
+                        * page.
+                        */
                        bio_add_page(bio, page, PAGE_SIZE, 0);
                }
                if (bytes_left < PAGE_SIZE) {