[PATCH v12 0/8] netfs: Use a bvecq chain position abstraction

[David Howells <dhowells@redhat.com>]

Hi Christian,

Could you pull these patches please into your vfs-7.4.netfs branch?  This
is the fourth of five batches.  The primary purpose of this batch is to add
an abstraction for a position in a bvecq chain and make use of it.

With that in mind, this patchset does the following:

 (1) Add a struct, bvecq_pos, to refer to a position in a bvecq chain.
     This is a tuple of ( bvecq pointer, slot and offset } and the position
     struct holds (for now) a ref on the bvecq pointed to.

 (2) Change unbuffered/DIO to extract the supplied user buffers into a
     bvecq chain rather than a bio_vec[] up front.  This means that
     netfslib then uses bvecq chains for everything.

 (3) Add a folio count to the readahead_control struct and then makes
     readahead pre-create its buffer using that count to determine how many
     slots are required.

 (4) Change netfslib to use the bvecq_pos struct to keep track of the whole
     request buffer and various points in it where loading, dispatch and
     collection are taking place and to also keep track of the slice given
     to each subrequest.

This was split from v11 of a larger netfslib series[1].

The patches can also be found here:

	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=netfs-next-4

Thanks,
David

Changes
=======
ver #12)
- Split from v11 of "netfs: Keep track of folios in a segmented bio_vec[]
  chain"[1]

[1] https://lore.kernel.org/r/20260902173350.3468672-1-dhowells@redhat.com/

David Howells (8):
  mm: Make readahead store folio count in readahead_control
  netfs: Add a function to extract from an iter into a bvecq
  netfs: Make unbuffered/DIO read and write use bvecq
  netfs: Add some tools for managing a position in a bvecq chain
  netfs: Provide a func to load the readahead buffers into a bvecq chain
  netfs: Use bvecq_pos to hold the buffer positions
  netfs: Remove the rolling_buffer implementation
  netfs: Remove netfs_extract_user_iter()

 fs/afs/dir.c                   |   5 +-
 fs/afs/symlink.c               |   6 +-
 fs/cachefiles/io.c             |  12 -
 fs/netfs/Makefile              |   1 -
 fs/netfs/buffered_read.c       | 169 ++++++++------
 fs/netfs/bvecq.c               | 310 ++++++++++++++++++++++++++
 fs/netfs/direct_read.c         |  77 +++----
 fs/netfs/direct_write.c        |  67 +++---
 fs/netfs/internal.h            |   4 +-
 fs/netfs/iterator.c            | 392 ++++++++++-----------------------
 fs/netfs/misc.c                |  18 --
 fs/netfs/objects.c             |  16 +-
 fs/netfs/read_collect.c        |  92 ++++----
 fs/netfs/read_pgpriv2.c        |  87 +++++---
 fs/netfs/read_retry.c          |  86 ++++----
 fs/netfs/read_single.c         |  16 +-
 fs/netfs/rolling_buffer.c      | 182 ---------------
 fs/netfs/write_collect.c       |  55 ++---
 fs/netfs/write_issue.c         | 166 +++++++++-----
 fs/netfs/write_retry.c         |  61 +++--
 include/linux/bvecq.h          | 184 ++++++++++++++++
 include/linux/netfs.h          |  25 ++-
 include/linux/pagemap.h        |  10 +
 include/linux/rolling_buffer.h |  47 ----
 include/trace/events/netfs.h   |  32 ++-
 mm/readahead.c                 |   5 +
 26 files changed, 1195 insertions(+), 930 deletions(-)
 delete mode 100644 fs/netfs/rolling_buffer.c
 delete mode 100644 include/linux/rolling_buffer.h