827a746f40
netfs: fix test for whether we can skip read when writing beyond EOF
...
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: e1b1240c1fceph-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
2021-06-21 21:24:07 +01:00
19dee61381
netfs: Pass flags through to grab_cache_page_write_begin()
...
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: e1b1240c1flinux-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
2021-05-25 13:46:32 +01:00
53b776c77a
netfs: Miscellaneous fixes
...
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) <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/161789062190.6155.12711584466338493050.stgit@warthog.procyon.org.uk/ [1]
2021-04-26 23:23:41 +01:00
0246f3e573
netfs: Add a tracepoint to log failures that would be otherwise unseen
...
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 <dhowells@redhat.com>
Tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
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
2021-04-23 10:14:32 +01:00
726218fdc2
netfs: Define an interface to talk to a cache
...
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 <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
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
2021-04-23 10:14:32 +01:00
e1b1240c1f
netfs: Add write_begin helper
...
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 <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
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
2021-04-23 10:14:32 +01:00
289af54cc6
netfs: Gather stats
...
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 <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
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
2021-04-23 10:14:32 +01:00
77b4d2c631
netfs: Add tracepoints
...
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 <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
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
2021-04-23 10:14:32 +01:00
3d3c950467
netfs: Provide readahead and readpage netfs helpers
...
Add a pair of helper functions:
(*) netfs_readahead()
(*) netfs_readpage()
to do the work of handling a readahead or a readpage, where the page(s)
that form part of the request may be split between the local cache, the
server or just require clearing, and may be single pages and transparent
huge pages. This is all handled within the helper.
Note that while both will read from the cache if there is data present,
only netfs_readahead() will expand the request beyond what it was asked to
do, and only netfs_readahead() will write back to the cache.
netfs_readpage(), on the other hand, is synchronous and only fetches the
page (which might be a THP) it is asked for.
The netfs gives the helper parameters from the VM, the cache cookie it
wants to use (or NULL) and a table of operations (only one of which is
mandatory):
(*) expand_readahead() [optional]
Called to allow the netfs to request an expansion of a readahead
request to meet its own alignment requirements. This is done by
changing rreq->start and rreq->len.
(*) clamp_length() [optional]
Called to allow the netfs to cut down a subrequest to meet its own
boundary requirements. If it does this, the helper will generate
additional subrequests until the full request is satisfied.
(*) is_still_valid() [optional]
Called to find out if the data just read from the cache has been
invalidated and must be reread from the server.
(*) issue_op() [required]
Called to ask the netfs to issue a read to the server. The subrequest
describes the read. The read request holds information about the file
being accessed.
The netfs can cache information in rreq->netfs_priv.
Upon completion, the netfs should set the error, transferred and can
also set FSCACHE_SREQ_CLEAR_TAIL and then call
fscache_subreq_terminated().
(*) done() [optional]
Called after the pages have been unlocked. The read request is still
pinning the file and mapping and may still be pinning pages with
PG_fscache. rreq->error indicates any error that has been
accumulated.
(*) cleanup() [optional]
Called when the helper is disposing of a finished read request. This
allows the netfs to clear rreq->netfs_priv.
Netfs support is enabled with CONFIG_NETFS_SUPPORT=y. It will be built
even if CONFIG_FSCACHE=n and in this case much of it should be optimised
away, allowing the filesystem to use it even when caching is disabled.
Changes:
v5:
- Comment why netfs_readahead() is putting pages[2].
- Use page_file_mapping() rather than page->mapping[2].
- Use page_index() rather than page->index[2].
- Use set_page_fscache()[3] rather then SetPageFsCache() as this takes an
appropriate ref too[4].
v4:
- Folded in a kerneldoc comment fix.
- Folded in a fix for the error handling in the case that ENOMEM occurs.
- 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 <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
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/20210321014202.GF3420@casper.infradead.org/ [2]
Link: https://lore.kernel.org/r/2499407.1616505440@warthog.procyon.org.uk/ [3]
Link: https://lore.kernel.org/r/CAHk-=wh+2gbF7XEjYc=HV9w_2uVzVf7vs60BPz0gFA=+pUm3ww@mail.gmail.com/ [4]
Link: https://lore.kernel.org/r/160588497406.3465195.18003475695899726222.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161118136849.1232039.8923686136144228724.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161032290.2537118.13400578415247339173.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340394873.1303470.6237319335883242536.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539537375.286939.16642940088716990995.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653795430.2770958.4947584573720000554.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789076581.6155.6745849361504760209.stgit@warthog.procyon.org.uk/ # v6
2021-04-23 10:14:32 +01:00
Jeff Layton
David Howells