linux.git/fs/netfs, branch v5.15

netfs: Fix READ/WRITE confusion when calling iov_iter_xarray()

2021-10-05T10:22:06+00:00

Fix netfs_clear_unread() to pass READ to iov_iter_xarray() instead of WRITE
(the flag is about the operation accessing the buffer, not what sort of
access it is doing to the buffer).

Fixes: 3d3c95046742 ("netfs: Provide readahead and readpage netfs helpers")
Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: ceph-devel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: linux-nfs@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/162729351325.813557.9242842205308443901.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/162886603464.3940407.3790841170414793899.stgit@warthog.procyon.org.uk
Link: https://lore.kernel.org/r/163239074602.1243337.14154704004485867017.stgit@warthog.procyon.org.uk

netfs: fix test for whether we can skip read when writing beyond EOF

2021-06-21T20:24:07+00:00

It's not sufficient to skip reading when the pos is beyond the EOF.
There may be data at the head of the page that we need to fill in
before the write.

Add a new helper function that corrects and clarifies the logic of
when we can skip reads, and have it only zero out the part of the page
that won't have data copied in for the write.

Finally, don't set the page Uptodate after zeroing. It's not up to date
since the write data won't have been copied in yet.

[DH made the following changes:

 - Prefixed the new function with "netfs_".

 - Don't call zero_user_segments() for a full-page write.

 - Altered the beyond-last-page check to avoid a DIV instruction and got
   rid of then-redundant zero-length file check.
]

Fixes: e1b1240c1ff5f ("netfs: Add write_begin helper")
Reported-by: Andrew W Elble 
Signed-off-by: Jeff Layton 
Signed-off-by: David Howells 
Reviewed-by: Matthew Wilcox (Oracle) 
cc: ceph-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20210613233345.113565-1-jlayton@kernel.org/
Link: https://lore.kernel.org/r/162367683365.460125.4467036947364047314.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/162391826758.1173366.11794946719301590013.stgit@warthog.procyon.org.uk/ # v2

netfs: Make CONFIG_NETFS_SUPPORT auto-selected rather than manual

2021-05-25T12:48:04+00:00

Make the netfs helper library selected automatically by the things that use
it rather than being manually configured, even though it's required[1].

Fixes: 3a5829fefd3b ("netfs: Make a netfs helper module")
Reported-by: Geert Uytterhoeven 
Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/CAMuHMdXJZ7iNQE964CdBOU=vRKVMFzo=YF_eiwsGgqzuvZ+TuA@mail.gmail.com [1]
Link: https://lore.kernel.org/r/162090298141.3166007.2971118149366779916.stgit@warthog.procyon.org.uk # v1

netfs: Pass flags through to grab_cache_page_write_begin()

2021-05-25T12:46:32+00:00

In netfs_write_begin(), pass the AOP flags through to
grab_cache_page_write_begin() so that a request to use GFP_NOFS is
honoured.

Fixes: e1b1240c1ff5 ("netfs: Add write_begin helper")
Reported-by: Matthew Wilcox (Oracle) 
Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
Reviewed-by: Matthew Wilcox (Oracle) 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/162090295383.3165945.13595101698295243662.stgit@warthog.procyon.org.uk # v1

netfs: Miscellaneous fixes

2021-04-26T22:23:41+00:00

Fix some miscellaneous things in the new netfs lib[1]:

 (1) The kerneldoc for netfs_readpage() shouldn't say netfs_page().

 (2) netfs_readpage() can get an integer overflow on 32-bit when it
     multiplies page_index(page) by PAGE_SIZE.  It should use
     page_file_offset() instead.

 (3) netfs_write_begin() should use page_offset() to avoid the same
     overflow.

Note that netfs_readpage() needs to use page_file_offset() rather than
page_offset() as it may see swap-over-NFS.

Reported-by: Matthew Wilcox (Oracle) 
Signed-off-by: David Howells 
Reviewed-by: Matthew Wilcox (Oracle) 
Reviewed-by: Jeff Layton 
Link: https://lore.kernel.org/r/161789062190.6155.12711584466338493050.stgit@warthog.procyon.org.uk/ [1]

netfs: Add a tracepoint to log failures that would be otherwise unseen

2021-04-23T09:14:32+00:00

Add a tracepoint to log internal failures (such as cache errors) that we
don't otherwise want to pass back to the netfs.

Signed-off-by: David Howells 
Tested-by: Jeff Layton 
Tested-by: Dave Wysochanski 
Tested-By: Marc Dionne 
cc: Matthew Wilcox 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/161781048813.463527.1557000804674707986.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161789082749.6155.15498680577213140870.stgit@warthog.procyon.org.uk/ # v6

netfs: Define an interface to talk to a cache

2021-04-23T09:14:32+00:00

Add an interface to the netfs helper library for reading data from the
cache instead of downloading it from the server and support for writing
data just downloaded or cleared to the cache.

The API passes an iov_iter to the cache read/write routines to indicate the
data/buffer to be used.  This is done using the ITER_XARRAY type to provide
direct access to the netfs inode's pagecache.

When the netfs's ->begin_cache_operation() method is called, this must fill
in the cache_resources in the netfs_read_request struct, including the
netfs_cache_ops used by the helper lib to talk to the cache.  The helper
lib does not directly access the cache.

Changes:
v6:
- Call trace_netfs_read() after beginning the cache op so that the cookie
  debug ID can be logged[3].
- Don't record the error from writing to the cache.  We don't want to pass
  it back to the netfs[4].
- Fix copy-to-cache subreq amalgamation to not round up as it goes along
  otherwise it overcalculates the length of the write[5].

v5:
- Use end_page_fscache() rather than unlock_page_fscache()[2].

v4:
- Added flag to netfs_subreq_terminated() to indicate that the caller may
  have been running async and stuff that might sleep needs punting to a
  workqueue (can't use in_softirq()[1]).
- Add missing inc of netfs_n_rh_read stat.
- Move initial definition of fscache_begin_read_operation() elsewhere.
- Need to call op->begin_cache_operation() from netfs_write_begin().

Signed-off-by: David Howells 
Reviewed-and-tested-by: Jeff Layton 
Tested-by: Dave Wysochanski 
Tested-By: Marc Dionne 
cc: Matthew Wilcox 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20210216084230.GA23669@lst.de/ [1]
Link: https://lore.kernel.org/r/2499407.1616505440@warthog.procyon.org.uk/ [2]
Link: https://lore.kernel.org/r/161781045123.463527.14533348855710902201.stgit@warthog.procyon.org.uk/ [3]
Link: https://lore.kernel.org/r/161781046256.463527.18158681600085556192.stgit@warthog.procyon.org.uk/ [4]
Link: https://lore.kernel.org/r/161781047695.463527.7463536103593997492.stgit@warthog.procyon.org.uk/ [5]
Link: https://lore.kernel.org/r/161118141321.1232039.8296910406755622458.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161036700.2537118.11170748455436854978.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340399569.1303470.1138884774643385730.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539542874.286939.13337898213448136687.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653799826.2770958.9015430297426331950.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789081462.6155.3853904866933313256.stgit@warthog.procyon.org.uk/ # v6

netfs: Add write_begin helper

2021-04-23T09:14:32+00:00

Add a helper to do the pre-reading work for the netfs write_begin address
space op.

Changes
v6:
- Fixed a missing rreq put in netfs_write_begin()[3].
- Use DEFINE_READAHEAD()[4].

v5:
- Made the wait for PG_fscache in netfs_write_begin() killable[2].

v4:
- Added flag to netfs_subreq_terminated() to indicate that the caller may
  have been running async and stuff that might sleep needs punting to a
  workqueue (can't use in_softirq()[1]).

Signed-off-by: David Howells 
Reviewed-and-tested-by: Jeff Layton 
Tested-by: Dave Wysochanski 
Tested-By: Marc Dionne 
cc: Matthew Wilcox 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20210216084230.GA23669@lst.de/ [1]
Link: https://lore.kernel.org/r/2499407.1616505440@warthog.procyon.org.uk/ [2]
Link: https://lore.kernel.org/r/161781042127.463527.9154479794406046987.stgit@warthog.procyon.org.uk/ [3]
Link: https://lore.kernel.org/r/1234933.1617886271@warthog.procyon.org.uk/ [4]
Link: https://lore.kernel.org/r/160588543960.3465195.2792938973035886168.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161118140165.1232039.16418853874312234477.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161035539.2537118.15674887534950908530.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340398368.1303470.11242918276563276090.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539541541.286939.1889738674057013729.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653798616.2770958.17213315845968485563.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789080530.6155.1011847312392330491.stgit@warthog.procyon.org.uk/ # v6

netfs: Gather stats

2021-04-23T09:14:32+00:00

Gather statistics from the netfs interface that can be exported through a
seqfile.  This is intended to be called by a later patch when viewing
/proc/fs/fscache/stats.

Signed-off-by: David Howells 
Reviewed-and-tested-by: Jeff Layton 
Tested-by: Dave Wysochanski 
Tested-By: Marc Dionne 
cc: Matthew Wilcox 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/161118139247.1232039.10556850937548511068.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161034669.2537118.2761232524997091480.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340397101.1303470.17581910581108378458.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539539959.286939.6794352576462965914.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653797700.2770958.5801990354413178228.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789079281.6155.17141344853277186500.stgit@warthog.procyon.org.uk/ # v6

netfs: Add tracepoints

2021-04-23T09:14:32+00:00

Add three tracepoints to track the activity of the read helpers:

 (1) netfs/netfs_read

     This logs entry to the read helpers and also expansion of the range in
     a readahead request.

 (2) netfs/netfs_rreq

     This logs the progress of netfs_read_request objects which track
     read requests.  A read request may be a compound of multiple
     subrequests.

 (3) netfs/netfs_sreq

     This logs the progress of netfs_read_subrequest objects, which track
     the contributions from various sources to a read request.

Signed-off-by: David Howells 
Reviewed-and-tested-by: Jeff Layton 
Tested-by: Dave Wysochanski 
Tested-By: Marc Dionne 
cc: Matthew Wilcox 
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/161118138060.1232039.5353374588021776217.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161033468.2537118.14021843889844001905.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340395843.1303470.7355519662919639648.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539538693.286939.10171713520419106334.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653796447.2770958.1870655382450862155.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789078003.6155.17814844411672989942.stgit@warthog.procyon.org.uk/ # v6