[GIT PULL] vfs netfs

From: Christian Brauner
Date: Fri Sep 13 2024 - 12:57:40 EST

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Hey Linus,

/* Summary */

This contains the work to improve read/write performance for the new
netfs library.

The main performance enhancing changes are:

- Define a structure, struct folio_queue, and a new iterator type,
ITER_FOLIOQ, to hold a buffer as a replacement for ITER_XARRAY. See
that patch for questions about naming and form.

ITER_FOLIOQ is provided as a replacement for ITER_XARRAY. The
problem with an xarray is that accessing it requires the use of a
lock (typically the RCU read lock) - and this means that we can't
supply iterate_and_advance() with a step function that might sleep
(crypto for example) without having to drop the lock between
pages. ITER_FOLIOQ is the iterator for a chain of folio_queue
structs, where each folio_queue holds a small list of folios. A
folio_queue struct is a simpler structure than xarray and is not
subject to concurrent manipulation by the VM. folio_queue is used
rather than a bvec[] as it can form lists of indefinite size,
adding to one end and removing from the other on the fly.

- Provide a copy_folio_from_iter() wrapper.

- Make cifs RDMA support ITER_FOLIOQ.

- Use folio queues in the write-side helpers instead of xarrays.

- Add a function to reset the iterator in a subrequest.

- Simplify the write-side helpers to use sheaves to skip gaps rather
than trying to work out where gaps are.

- In afs, make the read subrequests asynchronous, putting them into work
items to allow the next patch to do progressive unlocking/reading.

- Overhaul the read-side helpers to improve performance.

- Fix the caching of a partial block at the end of a file.

- Allow a store to be cancelled.

Then some changes for cifs to make it use folio queues instead of
xarrays for crypto bufferage:

- Use raw iteration functions rather than manually coding iteration when
hashing data.

- Switch to using folio_queue for crypto buffers.

- Remove the xarray bits.

Make some adjustments to the /proc/fs/netfs/stats file such that:

- All the netfs stats lines begin 'Netfs:' but change this to something
a bit more useful.

- Add a couple of stats counters to track the numbers of skips and waits
on the per-inode writeback serialisation lock to make it easier to
check for this as a source of performance loss.

Miscellaneous work:

- Ensure that the sb_writers lock is taken around
vfs_{set,remove}xattr() in the cachefiles code.

- Reduce the number of conditional branches in netfs_perform_write().

- Move the CIFS_INO_MODIFIED_ATTR flag to the netfs_inode struct and
remove cifs_post_modify().

- Move the max_len/max_nr_segs members from netfs_io_subrequest to
netfs_io_request as they're only needed for one subreq at a time.

- Add an 'unknown' source value for tracing purposes.

- Remove NETFS_COPY_TO_CACHE as it's no longer used.

- Set the request work function up front at allocation time.

- Use bh-disabling spinlocks for rreq->lock as cachefiles completion may
be run from block-filesystem DIO completion in softirq context.

- Remove fs/netfs/io.c.

/* Testing */

gcc version 14.2.0 (Debian 14.2.0-3)
Debian clang version 16.0.6 (27+b1)

All patches are based on the vfs-6.11-rc7.fixes merge to bring in prerequisite
fixes in individual filesystems. All of this has been sitting in linux-next. No
build failures or warnings were observed.

/* Conflicts */

Merge conflicts with mainline
=============================

No known merge conflicts.

This has now a merge conflict with main due to some rather late cifs fixes.
This can be resolved by:

git rm fs/netfs/io.c

and then:

diff --cc fs/smb/client/cifssmb.c
index cfae2e918209,04f2a5441a89..d0df0c17b18f
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@@ -1261,16 -1261,6 +1261,14 @@@ openRetry
return rc;
}

+static void cifs_readv_worker(struct work_struct *work)
+{
+ struct cifs_io_subrequest *rdata =
+ container_of(work, struct cifs_io_subrequest, subreq.work);
+
- netfs_subreq_terminated(&rdata->subreq,
- (rdata->result == 0 || rdata->result == -EAGAIN) ?
- rdata->got_bytes : rdata->result, true);
++ netfs_read_subreq_terminated(&rdata->subreq, rdata->result, false);
+}
+
static void
cifs_readv_callback(struct mid_q_entry *mid)
{
@@@ -1323,21 -1306,11 +1321,23 @@@
rdata->result = -EIO;
}

- if (rdata->result == 0 || rdata->result == -EAGAIN)
- iov_iter_advance(&rdata->subreq.io_iter, rdata->got_bytes);
+ if (rdata->result == -ENODATA) {
+ __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
+ rdata->result = 0;
+ } else {
- if (rdata->got_bytes < rdata->actual_len &&
- rdata->subreq.start + rdata->subreq.transferred + rdata->got_bytes ==
- ictx->remote_i_size) {
++ size_t trans = rdata->subreq.transferred + rdata->got_bytes;
++ if (trans < rdata->subreq.len &&
++ rdata->subreq.start + trans == ictx->remote_i_size) {
+ __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
+ rdata->result = 0;
+ }
+ }
+
rdata->credits.value = 0;
+ rdata->subreq.transferred += rdata->got_bytes;
- netfs_read_subreq_terminated(&rdata->subreq, rdata->result, false);
++ trace_netfs_sreq(&rdata->subreq, netfs_sreq_trace_io_progress);
+ INIT_WORK(&rdata->subreq.work, cifs_readv_worker);
+ queue_work(cifsiod_wq, &rdata->subreq.work);
release_mid(mid);
add_credits(server, &credits, 0);
}
diff --cc fs/smb/client/smb2pdu.c
index 88dc49d67037,95377bb91950..bb8ecbbe78af
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@@ -4614,6 -4613,10 +4613,8 @@@ smb2_readv_callback(struct mid_q_entry
server->credits, server->in_flight,
0, cifs_trace_rw_credits_read_response_clear);
rdata->credits.value = 0;
+ rdata->subreq.transferred += rdata->got_bytes;
- if (rdata->subreq.start + rdata->subreq.transferred >= rdata->subreq.rreq->i_size)
- __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
+ trace_netfs_sreq(&rdata->subreq, netfs_sreq_trace_io_progress);
INIT_WORK(&rdata->subreq.work, smb2_readv_worker);
queue_work(cifsiod_wq, &rdata->subreq.work);
release_mid(mid);

Merge conflicts with other trees
================================

No known merge conflicts.

The following changes since commit 4356ab331c8f0dbed0f683abde345cd5503db1e4:

Merge tag 'vfs-6.11-rc7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs (2024-09-04 09:33:57 -0700)

are available in the Git repository at:

git@xxxxxxxxxxxxxxxxxxx:pub/scm/linux/kernel/git/vfs/vfs tags/vfs-6.12.netfs

for you to fetch changes up to 4b40d43d9f951d87ae8dc414c2ef5ae50303a266:

docs: filesystems: corrected grammar of netfs page (2024-09-12 12:20:43 +0200)

Please consider pulling these changes from the signed vfs-6.12.netfs tag.

Thanks!
Christian

----------------------------------------------------------------
vfs-6.12.netfs

----------------------------------------------------------------
Christian Brauner (1):
Merge branch 'netfs-writeback' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into vfs.netfs

David Howells (24):
cachefiles: Fix non-taking of sb_writers around set/removexattr
netfs: Adjust labels in /proc/fs/netfs/stats
netfs: Record contention stats for writeback lock
netfs: Reduce number of conditional branches in netfs_perform_write()
netfs, cifs: Move CIFS_INO_MODIFIED_ATTR to netfs_inode
netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream
netfs: Reserve netfs_sreq_source 0 as unset/unknown
netfs: Remove NETFS_COPY_TO_CACHE
netfs: Set the request work function upon allocation
netfs: Use bh-disabling spinlocks for rreq->lock
mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of folios
iov_iter: Provide copy_folio_from_iter()
cifs: Provide the capability to extract from ITER_FOLIOQ to RDMA SGEs
netfs: Use new folio_queue data type and iterator instead of xarray iter
netfs: Provide an iterator-reset function
netfs: Simplify the writeback code
afs: Make read subreqs async
netfs: Speed up buffered reading
netfs: Remove fs/netfs/io.c
cachefiles, netfs: Fix write to partial block at EOF
netfs: Cancel dirty folios that have no storage destination
cifs: Use iterate_and_advance*() routines directly for hashing
cifs: Switch crypto buffer to use a folio_queue rather than an xarray
cifs: Don't support ITER_XARRAY

Dennis Lam (1):
docs: filesystems: corrected grammar of netfs page

Documentation/filesystems/netfs_library.rst | 2 +-
fs/9p/vfs_addr.c | 11 +-
fs/afs/file.c | 30 +-
fs/afs/fsclient.c | 9 +-
fs/afs/write.c | 4 +-
fs/afs/yfsclient.c | 9 +-
fs/cachefiles/io.c | 19 +-
fs/cachefiles/xattr.c | 34 +-
fs/ceph/addr.c | 76 +--
fs/netfs/Makefile | 4 +-
fs/netfs/buffered_read.c | 766 ++++++++++++++++----------
fs/netfs/buffered_write.c | 309 +++++------
fs/netfs/direct_read.c | 147 ++++-
fs/netfs/internal.h | 43 +-
fs/netfs/io.c | 804 ----------------------------
fs/netfs/iterator.c | 50 ++
fs/netfs/main.c | 7 +-
fs/netfs/misc.c | 94 ++++
fs/netfs/objects.c | 16 +-
fs/netfs/read_collect.c | 544 +++++++++++++++++++
fs/netfs/read_pgpriv2.c | 264 +++++++++
fs/netfs/read_retry.c | 256 +++++++++
fs/netfs/stats.c | 27 +-
fs/netfs/write_collect.c | 246 +++------
fs/netfs/write_issue.c | 93 ++--
fs/nfs/fscache.c | 19 +-
fs/nfs/fscache.h | 7 +-
fs/smb/client/cifsencrypt.c | 144 +----
fs/smb/client/cifsglob.h | 4 +-
fs/smb/client/cifssmb.c | 6 +-
fs/smb/client/file.c | 96 ++--
fs/smb/client/smb2ops.c | 219 ++++----
fs/smb/client/smb2pdu.c | 27 +-
fs/smb/client/smbdirect.c | 82 +--
include/linux/folio_queue.h | 156 ++++++
include/linux/iov_iter.h | 104 ++++
include/linux/netfs.h | 46 +-
include/linux/uio.h | 18 +
include/trace/events/netfs.h | 144 +++--
lib/iov_iter.c | 240 ++++++++-
lib/kunit_iov_iter.c | 259 +++++++++
lib/scatterlist.c | 69 ++-
42 files changed, 3520 insertions(+), 1984 deletions(-)
delete mode 100644 fs/netfs/io.c
create mode 100644 fs/netfs/read_collect.c
create mode 100644 fs/netfs/read_pgpriv2.c
create mode 100644 fs/netfs/read_retry.c
create mode 100644 include/linux/folio_queue.h

Next message: Shakeel Butt: "Re: [PATCH] mm/memcontrol: add per-memcg pgpgin/pswpin counter"
Previous message: Luis Chamberlain: "Re: [RESEND PATCH v2] params: Annotate struct module_param_attrs with __counted_by()"
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