In preparation to supporting dma-buf backed iterators and bios,
introduce bio_iov_iter_set() which attempts to set up the bio directly
from the given iterator. For now, it only supports bvec and expects
users to check the result and fall back to other means if fails, but
later we'll add more types.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/4686a0e47fc14f3f888967a80d45a6f66044f1e0.1785596451.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Some bio completion handlers need to run from preemptible task context,
but bio_endio() may be called from IRQ context (e.g., buffer_head
writeback). Callers need a way to ensure their callback eventually runs
from a sleepable context. Add infrastructure for that, in two forms:

  1. BIO_COMPLETE_IN_TASK, a bio flag the submitter sets when it knows
     in advance that its callback needs task context (e.g., dropbehind
     writeback). bio_endio() sees the flag and offloads completion to a
     worker automatically.

  2. bio_complete_in_task(), a helper that completion callbacks can
     invoke from within bi_end_io() when the deferral decision is
     dynamic (e.g., fserror reporting).

Both share a per-CPU list drained by a work item on a WQ_PERCPU
workqueue. Producers push the bio onto the local CPU's list and schedule
the work item, which then dispatches each bio's bi_end_io() from task
context.

Both methods are gated on bio_in_atomic(), which returns true in any
context where a sleeping bi_end_io() is unsafe, including
non-preemptible task context.

Two CPU hotplug callbacks are used to drain remaining bios from the
departing CPU's batch, while maintaining the per-CPU behavior. The
CPUHP_AP_ONLINE_DYN callback disables the per-CPU work item while the
CPU is still online, preventing it from running on an unbound worker
later. CPUHP_BP_PREPARE_DYN then drains any bios added between disabling
the work item and CPU offline.

Link: https://lore.kernel.org/all/20260409160243.1008358-1-hch@lst.de/
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260730-blk-dontcache-v7-2-3e8e6850068d@columbia.edu
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Move the atomic context detection logic from erofs's z_erofs_in_atomic()
into the block layer as bio_in_atomic(). This helper returns true when
the current context is unsafe for sleeping bio completion handlers (e.g.,
hard/soft IRQ, preempt-disabled).

The logic was originally added to erofs in commit c99fab6e80b7 ("erofs:
fix atomic context detection when !CONFIG_DEBUG_LOCK_ALLOC"). A
subsequent patch will use it in the block layer's bio completion
infrastructure, so move it to include/linux/bio.h where both subsystems
can share it.

Convert erofs to call the new bio_in_atomic() directly.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260730-blk-dontcache-v7-1-3e8e6850068d@columbia.edu
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The bio-based drivers don't necessarily check the alignment split, and
stacking block drivers don't always handle a misalignment detected after
submitting the bio. Validate user vectors against the device's
dma_alignment as the bio is built from the iov_iter, rejecting
misaligned early with -EINVAL.

Cc: stable@vger.kernel.org
Fixes: 5ff3f74e145a ("block: simplify direct io validity check")
Fixes: 7eac33186957 ("iomap: simplify direct io validity check")
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://patch.msgid.link/20260720201057.1862857-6-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull block updates from Jens Axboe:

 - NVMe pull request via Keith:
     - Per-controller admin and IO timeout sysfs attributes, and
       letting the block layer set request timeouts (Maurizio,
       Maximilian)
     - Multipath passthrough iostats, and PCI P2PDMA enablement for
       multipath devices (Keith, Kiran)
     - A new diag sysfs attribute group exporting per-controller
       counters (retries, multipath failover, error counters, requeue
       and failure counts, reset and reconnect events) (Nilay)
     - FDP configuration validation and bounds check fixes (liuxixin)
     - Various nvmet fixes, including a pre-auth out-of-bounds read in
       the Discovery Get Log Page handler, auth payload bounds
       validation, and tcp error-path leak fixes (Bryam, Tianchu,
       Geliang)
     - nvme-tcp lockdep and workqueue fixes (Shin'ichiro, Kuniyuki,
       Eric)
     - Assorted other fixes and cleanups (John, Yao, Chao, Mateusz,
       Achkinazi, Wentao)

 - MD pull request via Yu Kuai:
     - raid1/raid10 fixes for a deadlock in the read error recovery
       path, error-path detection and bio accounting with cloned bios,
       and an nr_pending leak in the REQ_ATOMIC bad-block error path
       (Abd-Alrhman)
     - PCI P2PDMA propagation from member devices to the RAID device
       (Kiran)
     - dm-raid bio requeue fix, and various smaller fixes and cleanups
       (Benjamin, Chen, Li, Thorsten)

 - Enable Clang lock context analysis for the block layer, with the
   accompanying annotations across queue limits, the blk_holder_ops
   callbacks, crypto, cgroup, iocost, kyber and mq-deadline (Bart)

 - Block status code infrastructure work: a tagged status table, a
   str_to_blk_op() helper, a bio_endio_status() helper, and on top of
   that a new configurable block-layer error injection facility
   (Christoph)

 - DRBD netlink rework, replacing the genl_magic machinery with explicit
   netlink serialization and moving the DRBD UAPI headers to
   include/uapi/linux/ (Christoph Böhmwalder)

 - bvec improvements: a bvec_folio() helper and making the bvec_iter
   helpers proper inline functions (Willy, Christoph)

 - ublk cleanups and a canceling-flag fix for the disk-not-allocated
   case (Caleb, Ming)

 - Partition handling fixes: bound the AIX pp_count scan, fix an of_node
   refcount leak, and replace __get_free_page() with kmalloc() (Bryam,
   Wentao, Mike)

 - Convert numa_node to int in blk_mq_hw_ctx and ->init_request, and add
   WQ_PERCPU to the block workqueue users (Mateusz, Marco)

 - Block statistics and tracing: propagate in-flight to the whole disk
   on partition IO, export passthrough stats, and a new
   block_rq_tag_wait tracepoint (Tang, Keith, Aaron)

 - A round of removals, unexports and cleanups across bio, direct-io and
   the bvec helpers (Christoph)

 - Various driver fixes (mtip32xx use-after-free, rbd snap_count
   validation and strscpy conversion, nbd socket lockdep reclassify,
   virtio-blk zone report clamp, floppy) and a batch of MAINTAINERS
   email/list updates (Coly, Li, Yu, Christoph Böhmwalder)

 - Other little fixes and cleanups all over

* tag 'for-7.2/block-20260615' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux: (117 commits)
  MAINTAINERS: Update Coly Li's email address
  block: check bio split for unaligned bvec
  nbd: Reclassify sockets to avoid lockdep circular dependency
  block: add configurable error injection
  block: add a str_to_blk_op helper
  block: add a "tag" for block status codes
  block: add a macro to initialize the status table
  floppy: Drop unused pnp driver data
  block: propagate in_flight to whole disk on partition I/O
  virtio-blk: clamp zone report to the report buffer capacity
  block: optimize I/O merge hot path with unlikely() hints
  drivers/block/rbd: Use strscpy() to copy strings into arrays
  partitions: aix: bound the pp_count scan to the ppe array
  block: Enable lock context analysis
  block/mq-deadline: Make the lock context annotations compatible with Clang
  block/Kyber: Make the lock context annotations compatible with Clang
  block/blk-mq-debugfs: Improve lock context annotations
  block/blk-iocost: Inline iocg_lock() and iocg_unlock()
  block/blk-iocost: Split ioc_rqos_throttle()
  block/crypto: Annotate the crypto functions
  ...

Pull iomap updates from Christian Brauner:

 - Add the vfs infrastructure required to implement fs-verity support
   for XFS with a post-EOF merkle tree: fsverity generates and stores a
   zero-block hash, and iomap learns to verify data on buffered reads,
   to handle fsverity during writeback via the new IOMAP_F_FSVERITY
   flag, and to write fsverity metadata through iomap_fsverity_write().

 - Skip the memset of the iomap in iomap_iter() once the iteration is
   done. In high-IOPS scenarios (4k randread NVMe polling via io_uring)
   the pointless memset wasted memory write bandwidth; this improves
   IOPS by about 5% on ext4 and xfs.

 - Add balance_dirty_pages_ratelimited() to iomap_zero_iter(), aligning
   it with iomap_write_iter(). This prepares for the exFAT iomap
   conversion where zeroing beyond valid_size can trigger large-scale
   zeroing operations that caused memory pressure without throttling.

 - Remove the over-strict inline data boundary check. If a filesystem
   provides a valid inline_data pointer and length there is no reason to
   require that inline data must not cross a page boundary.

 - Don't make REQ_POLLED imply REQ_NOWAIT, matching the earlier
   equivalent block layer fix: there are valid cases to poll for I/O
   completion without REQ_NOWAIT, and REQ_NOWAIT for file system writes
   is currently not supported as writes aren't idempotent.

 - Introduce IOMAP_F_ZERO_TAIL for filesystems that maintain a separate
   valid data length (exFAT, NTFS). For a write starting at or beyond
   valid_size, __iomap_write_begin() now zeroes only the tail portion of
   the block while preserving valid data before it, instead of leaving
   stale data in the page cache. The flag is also added to the iomap
   trace event strings.

* tag 'vfs-7.2-rc1.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  iomap: Add IOMAP_F_ZERO_TAIL flag to trace event strings
  iomap: introduce iomap_fsverity_write() for writing fsverity metadata
  iomap: teach iomap to read files with fsverity
  iomap: introduce IOMAP_F_FSVERITY and teach writeback to handle fsverity
  fsverity: generate and store zero-block hash
  iomap: introduce IOMAP_F_ZERO_TAIL flag
  iomap: don't make REQ_POLLED imply REQ_NOWAIT
  iomap: remove over-strict inline data boundary check
  iomap: add dirty page control to iomap_zero_iter
  iomap: avoid memset iomap when iter is done

This is a simple helper which replaces page_folio(bvec->bv_page).
Minor improvement in readability, but the real motivation is to reduce
the number of references to bvec->bv_page so that it can be changed
with less work.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Leon Romanovsky <leon@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: William Kucharski <william.kucharski@linux.dev>
Link: https://patch.msgid.link/20260528175905.1102280-2-willy@infradead.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add a helper that sets bi_status and call bio_endio() as that is a very
common pattern and convert the core block code over to it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Md Haris Iqbal <haris.iqbal@linux.dev>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Link: https://patch.msgid.link/20260528084632.2505277-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20260527150646.2349405-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Commit abb30460bda2 ("block: mark bio_wouldblock_error() bio with
BIO_QUIET") added this to suppress buffer_head warnings, but neither
when this commit was added nor now any buffer_head using code actually
ever sets REQ_NOWAIT which can lead to BLK_STS_AGAIN.

Remove the special handling for now.  If we ever plan to use REQ_NOWAIT
for buffer_head based I/O we're better off handling BLK_STS_AGAIN in
the completion handler as it actually needs to retry the I/O as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260518063336.507369-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>