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: 9d294a6 ("btrfs: zoned: enable to mount ZONED incompat flag") CC: stable@vger.kernel.org # 5.12.x: e380adf: 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>

Author: morbidrsa

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);
@@ -432,16 +457,21 @@ 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;
 if (bio->bi_iter.bi_size)
 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) {