Merge tag 'for-6.0-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "Fixes:

   - check that subvolume is writable when changing xattrs from security
     namespace

   - fix memory leak in device lookup helper

   - update generation of hole file extent item when merging holes

   - fix space cache corruption and potential double allocations; this
     is a rare bug but can be serious once it happens, stable backports
     and analysis tool will be provided

   - fix error handling when deleting root references

   - fix crash due to assert when attempting to cancel suspended device
     replace, add message what to do if mount fails due to missing
     replace item

  Regressions:

   - don't merge pages into bio if their page offset is not contiguous

   - don't allow large NOWAIT direct reads, this could lead to short
     reads eg. in io_uring"

* tag 'for-6.0-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: add info when mount fails due to stale replace target
  btrfs: replace: drop assert for suspended replace
  btrfs: fix silent failure when deleting root reference
  btrfs: fix space cache corruption and potential double allocations
  btrfs: don't allow large NOWAIT direct reads
  btrfs: don't merge pages into bio if their page offset is not contiguous
  btrfs: update generation of hole file extent item when merging holes
  btrfs: fix possible memory leak in btrfs_get_dev_args_from_path()
  btrfs: check if root is readonly while setting security xattr

1 files changed, 29 insertions, 4 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index eed81a7e36a4..cf4f19e80e2f 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3233,7 +3233,7 @@ static int btrfs_bio_add_page(struct btrfs_bio_ctrl *bio_ctrl,
 	u32 bio_size = bio->bi_iter.bi_size;
 	u32 real_size;
 	const sector_t sector = disk_bytenr >> SECTOR_SHIFT;
-	bool contig;
+	bool contig = false;
 	int ret;
 
 	ASSERT(bio);
@@ -3242,10 +3242,35 @@ static int btrfs_bio_add_page(struct btrfs_bio_ctrl *bio_ctrl,
 	if (bio_ctrl->compress_type != compress_type)
 		return 0;
 
-	if (bio_ctrl->compress_type != BTRFS_COMPRESS_NONE)
+
+	if (bio->bi_iter.bi_size == 0) {
+		/* We can always add a page into an empty bio. */
+		contig = true;
+	} else if (bio_ctrl->compress_type == BTRFS_COMPRESS_NONE) {
+		struct bio_vec *bvec = bio_last_bvec_all(bio);
+
+		/*
+		 * The contig check requires the following conditions to be met:
+		 * 1) The pages are belonging to the same inode
+		 *    This is implied by the call chain.
+		 *
+		 * 2) The range has adjacent logical bytenr
+		 *
+		 * 3) The range has adjacent file offset
+		 *    This is required for the usage of btrfs_bio->file_offset.
+		 */
+		if (bio_end_sector(bio) == sector &&
+		    page_offset(bvec->bv_page) + bvec->bv_offset +
+		    bvec->bv_len == page_offset(page) + pg_offset)
+			contig = true;
+	} else {
+		/*
+		 * For compression, all IO should have its logical bytenr
+		 * set to the starting bytenr of the compressed extent.
+		 */
 		contig = bio->bi_iter.bi_sector == sector;
-	else
-		contig = bio_end_sector(bio) == sector;
+	}
+
 	if (!contig)
 		return 0;