Merge patch series "lazy bounce buffering for checksummed reads v3"

Christoph Hellwig <hch@lst.de> says:

This series improves performance and resource usage for reads from
devices that require stable pages due to checksumming on XFS.

Currently XFS unconditionally bounce buffers reads on such devices to
prevent user modifications to the buffer from corrupting the data,
leading to checksum failures.

This uses DRAM bandwidth and CPU cycles for copies that are not needed
most of the time, and due to the use of a bio_vec for the bounce
buffer to smaller than wanted and unaligned I/O sizes when using 4k
user pages (i.e. 1MB-4k I/O).

This series addresses this by reading without the bounce buffer first,
and then only allocating a buffer and reading into that again on an
initial checksum failure.  To accommodate for rare (or hypothetical?)
applications that have legitimate needs to frequently modify in-flight
buffers, a sysfs know is provided to revert to the old behavior.

NOTE/QUESTION TO SUBSYSTEM MAINTAINERS: The patches in this series are
split over 3 subsystems, and I'd love to hear from the maintainers
about their preferences for merging this.

* 'for-7.4/lazy-bounce-buffering' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  block,iomap: remove the old read side bounce buffering support
  xfs: log a message at mount time when using integrity protection
  xfs: add error injection for lazy bounce buffering
  xfs: add support for lazy direct read bounce buffering
  iomap,xfs: move integrity verification to the file system
  xfs: use BIO_COMPLETE_IN_TASK for bounce buffered read I/Os
  iomap: better read bounce buffering support
  block,iomap: fix protection information verification with initial bvec offset
  xfs: move PI generation into xfs_submit_zoned_bio
  iomap,xfs: move T10 PI handling for direct I/O into ->submit_io
  iomap: add a IOMAP_IOEND_INTEGRITY flag
  iomap: add a iomap_ioend_flags helper
  iomap: respect maximum I/O size in iomap_dio_bio_iter_one
  block: warn on too larger integrity allocations
  block: pass a maxlen argument to bio_iov_iter_get_pages
  block: add a bio_prepare_reissue helper
  block: export fs_bio_integrity_{alloc,free}
  block: split bio_iov_iter_bounce_write
  block: improve aligning down bios in bio_iov_iter_bounce_write
  block: cap atomic write size by PI buffer size constraints
  block: avoid integer overflows in max_integrity_io_size
  block: store GPT attributes as a raw value

Link: https://patch.msgid.link/20260909060924.1102037-1-hch@lst.de
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index fd5f0e95648e..66a91c8b1cb9 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -8,6 +8,7 @@
 #define AUTOFS_SUPER_MAGIC	0x0187
 #define CEPH_SUPER_MAGIC	0x00c36400
 #define CODA_SUPER_MAGIC	0x73757245
+#define CONFIGFS_MAGIC		0x62656570	/* some random number */
 #define CRAMFS_MAGIC		0x28cd3d45	/* some random number */
 #define CRAMFS_MAGIC_WEND	0x453dcd28	/* magic number with the wrong endianess */
 #define DEBUGFS_MAGIC          0x64626720