cachefiles: Add some subrequest tracepoints

Add some tracepoints into the cachefiles write paths.

Signed-off-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/20241216204124.3

cachefiles: Add some subrequest tracepoints

Add some tracepoints into the cachefiles write paths.

Signed-off-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
cc: [email protected]
Signed-off-by: Christian Brauner <[email protected]>

show more ...

cachefiles, netfs: Fix write to partial block at EOF

Because it uses DIO writes, cachefiles is unable to make a write to the
backing file if that write is not aligned to and sized according to the
b

cachefiles, netfs: Fix write to partial block at EOF

Because it uses DIO writes, cachefiles is unable to make a write to the
backing file if that write is not aligned to and sized according to the
backing file's DIO block alignment. This makes it tricky to handle a write
to the cache where the EOF on the network file is not correctly aligned.

To get around this, netfslib attempts to tell the driver it is calling how
much more data there is available beyond the EOF that it can use to pad the
write (netfslib preclears the part of the folio above the EOF). However,
it tries to tell the cache what the maximum length is, but doesn't
calculate this correctly; and, in any case, cachefiles actually ignores the
value and just skips the block.

Fix this by:

(1) Change the value passed to indicate the amount of extra data that can
be added to the operation (now ->submit_extendable_to). This is much
simpler to calculate as it's just the end of the folio minus the top
of the data within the folio - rather than having to account for data
spread over multiple folios.

(2) Make cachefiles add some of this data if the subrequest it is given
ends at the network file's i_size if the extra data is sufficient to
pad out to a whole block.

Signed-off-by: David Howells <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]/ # v2
Signed-off-by: Christian Brauner <[email protected]>

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netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream

Move max_len/max_nr_segs from struct netfs_io_subrequest to struct
netfs_io_stream as we only issue one subreq at a time a

netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream

Move max_len/max_nr_segs from struct netfs_io_subrequest to struct
netfs_io_stream as we only issue one subreq at a time and then don't need
these values again for that subreq unless and until we have to retry it -
in which case we want to renegotiate them.

Signed-off-by: David Howells <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]/ # v2
Signed-off-by: Christian Brauner <[email protected]>

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cachefiles: Set the max subreq size for cache writes to MAX_RW_COUNT

Set the maximum size of a subrequest that writes to cachefiles to be
MAX_RW_COUNT so that we don't overrun the maximum write we c

cachefiles: Set the max subreq size for cache writes to MAX_RW_COUNT

Set the maximum size of a subrequest that writes to cachefiles to be
MAX_RW_COUNT so that we don't overrun the maximum write we can make to the
backing filesystem.

Signed-off-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
Signed-off-by: Christian Brauner <[email protected]>

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netfs, cachefiles: Implement helpers for new write code

Implement the helpers for the new write code in cachefiles. There's now an
optional ->prepare_write() that allows the filesystem to set the p

netfs, cachefiles: Implement helpers for new write code

Implement the helpers for the new write code in cachefiles. There's now an
optional ->prepare_write() that allows the filesystem to set the parameters
for the next write, such as maximum size and maximum segment count, and an
->issue_write() that is called to initiate an (asynchronous) write
operation.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]

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netfs: Switch to using unsigned long long rather than loff_t

Switch to using unsigned long long rather than loff_t in netfslib to avoid
problems with the sign flipping in the maths when we're dealin

netfs: Switch to using unsigned long long rather than loff_t

Switch to using unsigned long long rather than loff_t in netfslib to avoid
problems with the sign flipping in the maths when we're dealing with the
byte at position 0x7fffffffffffffff.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: Ilya Dryomov <[email protected]>
cc: Xiubo Li <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]

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cachefiles: Fix signed/unsigned mixup

In __cachefiles_prepare_write(), the start and pos variables were made
unsigned 64-bit so that the casts in the checking could be got rid of -
which should be f

cachefiles: Fix signed/unsigned mixup

In __cachefiles_prepare_write(), the start and pos variables were made
unsigned 64-bit so that the casts in the checking could be got rid of -
which should be fine since absolute file offsets can't be negative, except
that an error code may be obtained from vfs_llseek(), which *would* be
negative. This breaks the error check.

Fix this for now by reverting pos and start to be signed and putting back
the casts. Unfortunately, the error value checks cannot be replaced with
IS_ERR_VALUE() as long might be 32-bits.

Fixes: 7097c96411d2 ("cachefiles: Fix __cachefiles_prepare_write()")
Reported-by: Simon Horman <[email protected]>
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Signed-off-by: David Howells <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Reviewed-by: Gao Xiang <[email protected]>
cc: Yiqun Leng <[email protected]>
cc: Jia Zhu <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]

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netfs: Fix interaction between write-streaming and cachefiles culling

An issue can occur between write-streaming (storing dirty data in partial
non-uptodate pages) and a cachefiles object being cull

netfs: Fix interaction between write-streaming and cachefiles culling

An issue can occur between write-streaming (storing dirty data in partial
non-uptodate pages) and a cachefiles object being culled to make space.
The problem occurs because the cache object is only marked in use while
there are files open using it. Once it has been released, it can be culled
and the cookie marked disabled.

At this point, a streaming write is permitted to occur (if the cache is
active, we require pages to be prefetched and cached), but the cache can
become active again before this gets flushed out - and then two effects can
occur:

(1) The cache may be asked to write out a region that's less than its DIO
block size (assumed by cachefiles to be PAGE_SIZE) - and this causes
one of two debugging statements to be emitted.

(2) netfs_how_to_modify() gets confused because it sees a page that isn't
allowed to be non-uptodate being uptodate and tries to prefetch it -
leading to a warning that PG_fscache is set twice.

Fix this by the following means:

(1) Add a netfs_inode flag to disallow write-streaming to an inode and set
it if we ever do local caching of that inode. It remains set for the
lifetime of that inode - even if the cookie becomes disabled.

(2) If the no-write-streaming flag is set, then make netfs_how_to_modify()
always want to prefetch instead.

(3) If netfs_how_to_modify() decides it wants to prefetch a folio, but
that folio has write-streamed data in it, then it requires the folio
be flushed first.

(4) Export a counter of the number of times we wanted to prefetch a
non-uptodate page, but found it had write-streamed data in it.

(5) Export a counter of the number of times we cancelled a write to the
cache because it didn't DIO align and remove the debug statements.

Reported-by: Marc Dionne <[email protected]>
Signed-off-by: David Howells <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]

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cachefiles: Fix __cachefiles_prepare_write()

Fix __cachefiles_prepare_write() to correctly determine whether the
requested write will fit correctly with the DIO alignment.

Reported-by: Gao Xiang <h

cachefiles: Fix __cachefiles_prepare_write()

Fix __cachefiles_prepare_write() to correctly determine whether the
requested write will fit correctly with the DIO alignment.

Reported-by: Gao Xiang <[email protected]>
Signed-off-by: David Howells <[email protected]>
Tested-by: Yiqun Leng <[email protected]>
Tested-by: Jia Zhu <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]

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netfs, cachefiles: Pass upper bound length to allow expansion

Make netfslib pass the maximum length to the ->prepare_write() op to tell
the cache how much it can expand the length of a write to. Th

netfs, cachefiles: Pass upper bound length to allow expansion

Make netfslib pass the maximum length to the ->prepare_write() op to tell
the cache how much it can expand the length of a write to. This allows a
write to the server at the end of a file to be limited to a few bytes
whilst writing an entire block to the cache (something required by direct
I/O).

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]

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fs: move kiocb_start_write() into vfs_iocb_iter_write()

In vfs code, sb_start_write() is usually called after the permission hook
in rw_verify_area(). vfs_iocb_iter_write() is an exception to this

fs: move kiocb_start_write() into vfs_iocb_iter_write()

In vfs code, sb_start_write() is usually called after the permission hook
in rw_verify_area(). vfs_iocb_iter_write() is an exception to this rule,
where kiocb_start_write() is called by its callers.

Move kiocb_start_write() from the callers into vfs_iocb_iter_write()
after the rw_verify_area() checks, to make them "start-write-safe".

The semantics of vfs_iocb_iter_write() is changed, so that the caller is
responsible for calling kiocb_end_write() on completion only if async
iocb was queued. The completion handlers of both callers were adapted
to this semantic change.

This is needed for fanotify "pre content" events.

Suggested-by: Jan Kara <[email protected]>
Suggested-by: Josef Bacik <[email protected]>
Signed-off-by: Amir Goldstein <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Josef Bacik <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

show more ...

cachefiles: use kiocb_{start,end}_write() helpers

Use helpers instead of the open coded dance to silence lockdep warnings.

Suggested-by: Jan Kara <[email protected]>
Signed-off-by: Amir Goldstein <amir7

cachefiles: use kiocb_{start,end}_write() helpers

Use helpers instead of the open coded dance to silence lockdep warnings.

Suggested-by: Jan Kara <[email protected]>
Signed-off-by: Amir Goldstein <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Jens Axboe <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

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fscache,cachefiles: add prepare_ondemand_read() callback

Add prepare_ondemand_read() callback dedicated for the on-demand read
scenario, so that callers from this scenario can be decoupled from
netf

fscache,cachefiles: add prepare_ondemand_read() callback

Add prepare_ondemand_read() callback dedicated for the on-demand read
scenario, so that callers from this scenario can be decoupled from
netfs_io_subrequest.

The original cachefiles_prepare_read() is now refactored to a generic
routine accepting a parameter list instead of netfs_io_subrequest.
There's no logic change, except that the debug id of subrequest and
request is removed from trace_cachefiles_prep_read().

Reviewed-by: Jeff Layton <[email protected]>
Signed-off-by: Jingbo Xu <[email protected]>
Acked-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Gao Xiang <[email protected]>

show more ...

cachefiles: implement on-demand read

Implement the data plane of on-demand read mode.

The early implementation [1] place the entry to
cachefiles_ondemand_read() in fscache_read(). However, fscache_

cachefiles: implement on-demand read

Implement the data plane of on-demand read mode.

The early implementation [1] place the entry to
cachefiles_ondemand_read() in fscache_read(). However, fscache_read()
can only detect if the requested file range is fully cache miss, whilst
we need to notify the user daemon as long as there's a hole inside the
requested file range.

Thus the entry is now placed in cachefiles_prepare_read(). When working
in on-demand read mode, once a hole detected, the read routine will send
a READ request to the user daemon. The user daemon needs to fetch the
data and write it to the cache file. After sending the READ request, the
read routine will hang there, until the READ request is handled by the
user daemon. Then it will retry to read from the same file range. If no
progress encountered, the read routine will fail then.

A new NETFS_SREQ_ONDEMAND flag is introduced to indicate that on-demand
read should be done when a cache miss encountered.

[1] https://lore.kernel.org/all/[email protected]/ #v8

Signed-off-by: Jeffle Xu <[email protected]>
Acked-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Gao Xiang <[email protected]>

show more ...

cachefiles: extract write routine

Extract the generic routine of writing data to cache files, and make it
generally available.

This will be used by the following patch implementing on-demand read
m

cachefiles: extract write routine

Extract the generic routine of writing data to cache files, and make it
generally available.

This will be used by the following patch implementing on-demand read
mode. Since it's called inside CacheFiles module, make the interface
generic and unrelated to netfs_cache_resources.

It is worth noting that, ki->inval_counter is not initialized after
this cleanup. It shall not make any visible difference, since
inval_counter is no longer used in the write completion routine, i.e.
cachefiles_write_complete().

Signed-off-by: Jeffle Xu <[email protected]>
Acked-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Gao Xiang <[email protected]>

show more ...

netfs: Finish off rename of netfs_read_request to netfs_io_request

Adjust helper function names and comments after mass rename of
struct netfs_read_*request to struct netfs_io_*request.

Changes
===

netfs: Finish off rename of netfs_read_request to netfs_io_request

Adjust helper function names and comments after mass rename of
struct netfs_read_*request to struct netfs_io_*request.

Changes
=======
ver #2)
- Make the changes in the docs also.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]

Link: https://lore.kernel.org/r/164622992433.3564931.6684311087845150271.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678196111.1200972.5001114956865989528.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692892567.2099075.13895804222087028813.stgit@warthog.procyon.org.uk/ # v3

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netfs: Rename netfs_read_*request to netfs_io_*request

Rename netfs_read_*request to netfs_io_*request so that the same structures
can be used for the write helpers too.

perl -p -i -e 's/netfs_read

netfs: Rename netfs_read_*request to netfs_io_*request

Rename netfs_read_*request to netfs_io_*request so that the same structures
can be used for the write helpers too.

perl -p -i -e 's/netfs_read_(request|subrequest)/netfs_io_$1/g' \
`git grep -l 'netfs_read_\(sub\|\)request'`
perl -p -i -e 's/nr_rd_ops/nr_outstanding/g' \
`git grep -l nr_rd_ops`
perl -p -i -e 's/nr_wr_ops/nr_copy_ops/g' \
`git grep -l nr_wr_ops`
perl -p -i -e 's/netfs_read_source/netfs_io_source/g' \
`git grep -l 'netfs_read_source'`
perl -p -i -e 's/netfs_io_request_ops/netfs_request_ops/g' \
`git grep -l 'netfs_io_request_ops'`
perl -p -i -e 's/init_rreq/init_request/g' \
`git grep -l 'init_rreq'`

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]

Link: https://lore.kernel.org/r/164622988070.3564931.7089670190434315183.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678195157.1200972.366609966927368090.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692891535.2099075.18435198075367420588.stgit@warthog.procyon.org.uk/ # v3

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fs: remove kiocb.ki_hint

This field is entirely unused now except for a tracepoint in f2fs, so
remove it.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Dave Chinner <[email protected]

fs: remove kiocb.ki_hint

This field is entirely unused now except for a tracepoint in f2fs, so
remove it.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Dave Chinner <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

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netfs, cachefiles: Add a method to query presence of data in the cache

Add a netfs_cache_ops method by which a network filesystem can ask the
cache about what data it has available and where so that

netfs, cachefiles: Add a method to query presence of data in the cache

Add a netfs_cache_ops method by which a network filesystem can ask the
cache about what data it has available and where so that it can make a
multipage read more efficient.

Signed-off-by: David Howells <[email protected]>
cc: [email protected]
Acked-by: Jeff Layton <[email protected]>
Reviewed-by: Rohith Surabattula <[email protected]>
Signed-off-by: Steve French <[email protected]>

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cachefiles: Calculate the blockshift in terms of bytes, not pages

Cachefiles keeps track of how much space is available on the backing
filesystem and refuses new writes permission to start if there

cachefiles: Calculate the blockshift in terms of bytes, not pages

Cachefiles keeps track of how much space is available on the backing
filesystem and refuses new writes permission to start if there isn't enough
(we especially don't want ENOSPC happening). It also tracks the amount of
data pending in DIO writes (cache->b_writing) and reduces the amount of
free space available by this amount before deciding if it can set up a new
write.

However, the old fscache I/O API was very much page-granularity dependent
and, as such, cachefiles's cache->bshift was meant to be a multiplier to
get from PAGE_SIZE to block size (ie. a blocksize of 512 would give a shift
of 3 for a 4KiB page) - and this was incorrectly being used to turn the
number of bytes in a DIO write into a number of blocks, leading to a
massive over estimation of the amount of data in flight.

Fix this by changing cache->bshift to be a multiplier from bytes to
blocksize and deal with quantities of blocks, not quantities of pages.

Fix also the rounding in the calculation in cachefiles_write() which needs
a "- 1" inserting.

Fixes: 047487c947e8 ("cachefiles: Implement the I/O routines")
Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
Link: https://lore.kernel.org/r/164251398954.3435901.7138806620218474123.stgit@warthog.procyon.org.uk/ # v1

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fscache, cachefiles: Display stats of no-space events

Add stat counters of no-space events that caused caching not to happen and
display in /proc/fs/fscache/stats.

Signed-off-by: David Howells <dho

fscache, cachefiles: Display stats of no-space events

Add stat counters of no-space events that caused caching not to happen and
display in /proc/fs/fscache/stats.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
Link: https://lore.kernel.org/r/163819653216.215744.17210522251617386509.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906958369.143852.7257100711818401748.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967166917.1823006.14842444049198947892.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021566184.640689.4417328329632709265.stgit@warthog.procyon.org.uk/ # v4

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cachefiles: Implement the I/O routines

Implement the I/O routines for cachefiles. There are two sets of routines
here: preparation and actual I/O.

Preparation for read involves looking to see whet

cachefiles: Implement the I/O routines

Implement the I/O routines for cachefiles. There are two sets of routines
here: preparation and actual I/O.

Preparation for read involves looking to see whether there is data present,
and how much. Netfslib tells us what it wants us to do and we have the
option of adjusting shrinking and telling it whether to read from the
cache, download from the server or simply clear a region.

Preparation for write involves checking for space and defending against
possibly running short of space, if necessary punching out a hole in the
file so that we don't leave old data in the cache if we update the
coherency information.

Then there's a read routine and a write routine. They wait for the cookie
state to move to something appropriate and then start a potentially
asynchronous direct I/O operation upon it.

Changes
=======
ver #2:
- Fix a misassigned variable[1].

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
Link: https://lore.kernel.org/YaZOCk9zxApPattb@archlinux-ax161/ [1]
Link: https://lore.kernel.org/r/163819647945.215744.17827962047487125939.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906954666.143852.1504887120569779407.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967163110.1823006.9206718511874339672.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021562168.640689.8802250542405732391.stgit@warthog.procyon.org.uk/ # v4

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cachefiles: Implement begin and end I/O operation

Implement the methods for beginning and ending an I/O operation.

When called to begin an I/O operation, we are guaranteed that the cookie
has reach

cachefiles: Implement begin and end I/O operation

Implement the methods for beginning and ending an I/O operation.

When called to begin an I/O operation, we are guaranteed that the cookie
has reached a certain stage (we're called by fscache after it has done a
suitable wait).

If a file is available, we paste a ref over into the cache resources for
the I/O routines to use. This means that the object can be invalidated
whilst the I/O is ongoing without the need to synchronise as the file
pointer in the object is replaced, but the file pointer in the cache
resources is unaffected.

Ending the operation just requires ditching any refs we have and dropping
the access guarantee that fscache got for us on the cookie.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
Link: https://lore.kernel.org/r/163819645033.215744.2199344081658268312.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906951916.143852.9531384743995679857.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967161222.1823006.4461476204800357263.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021559030.640689.3684291785218094142.stgit@warthog.procyon.org.uk/ # v4

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fs: get rid of the res2 iocb->ki_complete argument

The second argument was only used by the USB gadget code, yet everyone
pays the overhead of passing a zero to be passed into aio, where it
ends up

fs: get rid of the res2 iocb->ki_complete argument

The second argument was only used by the USB gadget code, yet everyone
pays the overhead of passing a zero to be passed into aio, where it
ends up being part of the aio res2 value.

Now that everybody is passing in zero, kill off the extra argument.

Reviewed-by: Darrick J. Wong <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

show more ...

cachefiles: Use file_inode() rather than accessing ->f_inode

Use the file_inode() helper rather than accessing ->f_inode directly.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Je

cachefiles: Use file_inode() rather than accessing ->f_inode

Use the file_inode() helper rather than accessing ->f_inode directly.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
cc: [email protected]
Link: https://lore.kernel.org/r/162431192403.2908479.4590814090994846904.stgit@warthog.procyon.org.uk/

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