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Cachefiles currently uses the backing filesystem's idea of what data is
held in a backing file and queries this by means of SEEK_DATA and
SEEK_HOLE. However, this means it does two seek operations on the backing
file for each individual read call it wants to prepare (unless the first
returns -ENXIO). Worse, the backing filesystem is at liberty to insert or
remove blocks of zeros in order to optimise its layout which may cause
false positives and false negatives.
The problem is that keeping track of what is dirty is tricky (if storing
info in xattrs, which may have limited capacity and must be read and
written as one piece) and expensive (in terms of diskspace at least) and is
basically duplicating what a filesystem does.
However, the most common write case, in which the application does {
open(O_TRUNC); write(); write(); ... write(); close(); } where each write
follows directly on from the previous and leaves no gaps in the file is
reasonably easy to detect and can be noted in the primary xattr as
CACHEFILES_CONTENT_ALL, indicating we have everything up to the object size
stored.
In this specific case, given that it is known that there are no holes in
the file, there's no need to call SEEK_DATA/HOLE or use any other mechanism
to track the contents. That speeds things up enormously.
Even when it is necessary to use SEEK_DATA/HOLE, it may not be necessary to
call it for each cache read subrequest generated.
Implement this by adding support for the CACHEFILES_CONTENT_ALL content
type (which is defined, but currently unused), which requires a slight
adjustment in how backing files are managed. Specifically, the driver
needs to know how much of the tail block is data and whether storing more
data will create a hole.
To this end, the way that the size of a backing file is managed is changed.
Currently, the backing file is expanded to strictly match the size of the
network file, but this can be changed to carry more useful information.
This makes two pieces of metadata available: xattr.object_size and the
backing file's i_size. Apply the following schema:
(a) i_size is always a multiple of the DIO block size.
(b) i_size is only updated to the end of the highest write stored. This
is used to work out if we are following on without leaving a hole.
(c) xattr.object_size is the size of the network filesystem file cached
in this backing file.
(d) xattr.object_size must point after the start of the last block
(unless both are 0).
(e) If xattr.object_size is at or after the block at the current end of
the backing file (ie. i_size), then we have all the contents of the
block (if xattr.content == CACHEFILES_CONTENT_ALL).
(f) If xattr.object_size is somewhere in the middle of the last block,
then the data following it is invalid and must be ignored.
(g) If data is added to the last block, then that block must be fetched,
modified and rewritten (it must be a buffered write through the
pagecache and not DIO).
(h) Writes to cache are rounded out to blocks on both sides and the
folios used as sources must contain data for any lower gap and must
have been cleared for any upper gap, and so will rewrite any
non-data area in the tail block.
To implement this, the following changes are made:
(1) cookie->object_size is no longer updated when writes are copied into
the pagecache, but rather only updated when a write request completes.
This prevents object size miscomparison when checking the xattr
causing the backing file to be invalidated (opening and marking the
backing file and modifying the pagecache run in parallel).
(2) The cache's current idea of the amount of data that should be stored
in the backing file is kept track of in object->object_size.
Possibly this is redundant with cookie->object_size, but the latter
gets updated in some addition circumstances.
(3) The size of the backing file at the start of a request is now tracked
in struct netfs_cache_resources so that the partial EOF block can be
located and cleaned.
(4) The cache block size is now used consistently rather than using
CACHEFILES_DIO_BLOCK_SIZE (4096).
(5) The backing file size is no longer adjusted when looking up an object.
(6) When shortening a file, if the new size is not block aligned, the part
beyond the new size is cleared. If the file is truncated to zero, the
content_info gets reset to CACHEFILES_CONTENT_NO_DATA.
(7) A new struct, fscache_occupancy, is instituted to track the region
being read. Netfslib allocates it and fills in the start and end of
the region to be read then calls the ->query_occupancy() method to
find and fill in the extents. It also indicates whether a recorded
extent contains data or just contains a region that's all zeros
(FSCACHE_EXTENT_DATA or FSCACHE_EXTENT_ZERO).
(8) The ->prepare_read() cache method is changed such that, if given, it
just limits the amount that can be read from the cache in one go. It
no longer indicates what source of read should be done; that
information is now obtained from ->query_occupancy().
(9) A new cache method, ->collect_write(), is added that is called when a
contiguous series of writes have completed and a discontiguity or the
end of the request has been hit. It it supplied with the start and
length of the write made to the backing file and can use this
information to update the cache metadata.
(10) cachefiles_query_occupancy() is altered to find the next two "extents"
of data stored in the backing file by doing SEEK_DATA/HOLE between the
bounds set - unless it is known that there are no holes, in which case
a whole-file first extent can be set.
(11) cachefiles_collect_write() is implemented to take the collated write
completion information and use this to update the cache metadata, in
particular working out whether there's now a hole in the backing file
requiring future use of SEEK_DATA/HOLE instead of just assuming the
data is all present.
It also uses fallocate(FALLOC_FL_ZERO_RANGE) to clean the part of a
partial block that extended beyond the old object size. It might be
better to perform a synchronous DIO write for this purpose, but that
would mandate an RMW cycle. Ideally, it should be all zeros anyway,
but, unfortunately, shared-writable mmap can interfere.
(12) cachefiles_begin_operation() is updated to note the current backing
file size and the cache DIO size.
(13) cachefiles_create_tmpfile() no longer expands the backing file when it
creates it.
(14) cachefiles_set_object_xattr() is changed to use object->object_size
rather than cookie->object_size.
(15) cachefiles_check_auxdata() is altered to actually store the content
type and to also set object->object_size. The cachefiles_coherency
tracepoint is also modified to display xattr.object_size.
(16) netfs_read_to_pagecache() is reworked. The cache ->prepare_read()
method is replaced with ->query_occupancy() as the arbiter of what
region of the file is read from where, and that retrieves up to two
occupied extents of the backing file at once.
The cache ->prepare_read() method is now repurposed to be the same as
the equivalent network filesystem method and allows the cache to limit
the size of the read before the iterator is prepared.
netfs_single_dispatch_read() is similarly modified.
(17) netfs_update_i_size() and afs_update_i_size() no longer call
fscache_update_cookie() to update cookie->object_size.
(18) Write collection now collates contiguous sequences of writes to the
cache and calls the cache ->collect_write() method.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260910220242.2165023-5-dhowells@redhat.com
Reviewed-by: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Add a tracepoint to log insufficient space errors.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260910220242.2165023-4-dhowells@redhat.com
Reviewed-by: Paulo Alcantara <pc@manguebit.org>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Use uoff_t instead of unsigned long long and loff_t for file positions that
can't be negative.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260909072105.1663687-2-dhowells@redhat.com
Reviewed-by: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Currently, trace_cachefiles_coherency() is being passed a pointer to a
__be64 lain over the coherency data in struct cachefiles_xattr so that it
can display the first 8 bytes. However, the data is of variable length and
could even be 0 bytes. This could lead to a UAF or KASAN warning.
Fix this by making sure the buffer has room for at least 8 bytes and that
those 8 bytes are pre-cleared.
Further, those bytes are not 8-byte aligned, so fix the tracepoint to
extract the data as four 2-byte words (they are 2-byte aligned) and
reassemble the __be64. The compiler will convert this into a single 8-byte
load where the CPU supports it.
Fixes: 229105e5cfd9 ("cachefiles: Add auxiliary data trace")
Link: https://sashiko.dev/#/patchset/20260810144746.574036-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260827134304.2075713-11-dhowells@redhat.com
Acked-by: Paulo Alcantara <pc@manguebit.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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It was an effort to enhance fscache as a kernel cache for lazy
pulling (at least according to previous Incremental FS discussion [1])
and EROFS over fscache was the in-tree user of this mode.
fscache has since evolved to be netfslib-oriented, serving network
filesystem inodes via the netfs library, but EROFS never acts as a
network filesystem and we need to cache golden filesystem images rather
than individual EROFS inodes.
Since EROFS over fscache is now removed, clean up netfs/fscache/
cachefiles upstream too.
[1] https://lore.kernel.org/r/CAOQ4uxi4dzxArY24YO=+kBCK2gGoq3Ptb8WkzCqSogPgU_R3dQ@mail.gmail.com
[dh] Fixed up comments on:
https://sashiko.dev/#/patchset/20260716103030.3065561-1-dhowells%40redhat.com
https://sashiko.dev/#/patchset/20260722130218.78958-1-dhowells%40redhat.com
Signed-off-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/1046393.1786544127@warthog.procyon.org.uk
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-erofs@lists.ozlabs.org
cc: bpf@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Update cachefiles trace event definitions to use u64 instead of
ino_t/unsigned long for inode number fields.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260304-iino-u64-v3-5-2257ad83d372@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add a display of the first 8 bytes of the downloaded auxiliary data and of
the on-disk stored auxiliary data as these are used in coherency
management. In the case of afs, this holds the data version number.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-17-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Clean up some whitespace in the cachefiles trace header.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-3-dhowells@redhat.com
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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We got the following issue in a fuzz test of randomly issuing the restore
command:
==================================================================
BUG: KASAN: slab-use-after-free in cachefiles_ondemand_daemon_read+0xb41/0xb60
Read of size 8 at addr ffff888122e84088 by task ondemand-04-dae/963
CPU: 13 PID: 963 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #564
Call Trace:
kasan_report+0x93/0xc0
cachefiles_ondemand_daemon_read+0xb41/0xb60
vfs_read+0x169/0xb50
ksys_read+0xf5/0x1e0
Allocated by task 116:
kmem_cache_alloc+0x140/0x3a0
cachefiles_lookup_cookie+0x140/0xcd0
fscache_cookie_state_machine+0x43c/0x1230
[...]
Freed by task 792:
kmem_cache_free+0xfe/0x390
cachefiles_put_object+0x241/0x480
fscache_cookie_state_machine+0x5c8/0x1230
[...]
==================================================================
Following is the process that triggers the issue:
mount | daemon_thread1 | daemon_thread2
------------------------------------------------------------
cachefiles_withdraw_cookie
cachefiles_ondemand_clean_object(object)
cachefiles_ondemand_send_req
REQ_A = kzalloc(sizeof(*req) + data_len)
wait_for_completion(&REQ_A->done)
cachefiles_daemon_read
cachefiles_ondemand_daemon_read
REQ_A = cachefiles_ondemand_select_req
msg->object_id = req->object->ondemand->ondemand_id
------ restore ------
cachefiles_ondemand_restore
xas_for_each(&xas, req, ULONG_MAX)
xas_set_mark(&xas, CACHEFILES_REQ_NEW)
cachefiles_daemon_read
cachefiles_ondemand_daemon_read
REQ_A = cachefiles_ondemand_select_req
copy_to_user(_buffer, msg, n)
xa_erase(&cache->reqs, id)
complete(&REQ_A->done)
------ close(fd) ------
cachefiles_ondemand_fd_release
cachefiles_put_object
cachefiles_put_object
kmem_cache_free(cachefiles_object_jar, object)
REQ_A->object->ondemand->ondemand_id
// object UAF !!!
When we see the request within xa_lock, req->object must not have been
freed yet, so grab the reference count of object before xa_unlock to
avoid the above issue.
Fixes: 0a7e54c1959c ("cachefiles: resend an open request if the read request's object is closed")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-5-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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This lets us see the correct trace output.
Fixes: c8383054506c ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-2-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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 <jlayton@kernel.org>
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20221124034212.81892-2-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
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Add tracepoints for on-demand read mode. Currently following tracepoints
are added:
OPEN request / COPEN reply
CLOSE request
READ request / CREAD reply
write through anonymous fd
release of anonymous fd
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20220425122143.56815-8-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
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Fscache/CacheFiles used to serve as a local cache for a remote
networking fs. A new on-demand read mode will be introduced for
CacheFiles, which can boost the scenario where on-demand read semantics
are needed, e.g. container image distribution.
The essential difference between these two modes is seen when a cache
miss occurs: In the original mode, the netfs will fetch the data from
the remote server and then write it to the cache file; in on-demand
read mode, fetching the data and writing it into the cache is delegated
to a user daemon.
As the first step, notify the user daemon when looking up cookie. In
this case, an anonymous fd is sent to the user daemon, through which the
user daemon can write the fetched data to the cache file. Since the user
daemon may move the anonymous fd around, e.g. through dup(), an object
ID uniquely identifying the cache file is also attached.
Also add one advisory flag (FSCACHE_ADV_WANT_CACHE_SIZE) suggesting that
the cache file size shall be retrieved at runtime. This helps the
scenario where one cache file contains multiple netfs files, e.g. for
the purpose of deduplication. In this case, netfs itself has no idea the
size of the cache file, whilst the user daemon should give the hint on
it.
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220509074028.74954-3-jefflexu@linux.alibaba.com
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull netfs updates from David Howells:
"Netfs prep for write helpers.
Having had a go at implementing write helpers and content encryption
support in netfslib, it seems that the netfs_read_{,sub}request
structs and the equivalent write request structs were almost the same
and so should be merged, thereby requiring only one set of
alloc/get/put functions and a common set of tracepoints.
Merging the structs also has the advantage that if a bounce buffer is
added to the request struct, a read operation can be performed to fill
the bounce buffer, the contents of the buffer can be modified and then
a write operation can be performed on it to send the data wherever it
needs to go using the same request structure all the way through. The
I/O handlers would then transparently perform any required crypto.
This should make it easier to perform RMW cycles if needed.
The potentially common functions and structs, however, by their names
all proclaim themselves to be associated with the read side of things.
The bulk of these changes alter this in the following ways:
- Rename struct netfs_read_{,sub}request to netfs_io_{,sub}request.
- Rename some enums, members and flags to make them more appropriate.
- Adjust some comments to match.
- Drop "read"/"rreq" from the names of common functions. For
instance, netfs_get_read_request() becomes netfs_get_request().
- The ->init_rreq() and ->issue_op() methods become ->init_request()
and ->issue_read(). I've kept the latter as a read-specific
function and in another branch added an ->issue_write() method.
The driver source is then reorganised into a number of files:
fs/netfs/buffered_read.c Create read reqs to the pagecache
fs/netfs/io.c Dispatchers for read and write reqs
fs/netfs/main.c Some general miscellaneous bits
fs/netfs/objects.c Alloc, get and put functions
fs/netfs/stats.c Optional procfs statistics.
and future development can be fitted into this scheme, e.g.:
fs/netfs/buffered_write.c Modify the pagecache
fs/netfs/buffered_flush.c Writeback from the pagecache
fs/netfs/direct_read.c DIO read support
fs/netfs/direct_write.c DIO write support
fs/netfs/unbuffered_write.c Write modifications directly back
Beyond the above changes, there are also some changes that affect how
things work:
- Make fscache_end_operation() generally available.
- In the netfs tracing header, generate enums from the symbol ->
string mapping tables rather than manually coding them.
- Add a struct for filesystems that uses netfslib to put into their
inode wrapper structs to hold extra state that netfslib is
interested in, such as the fscache cookie. This allows netfslib
functions to be set in filesystem operation tables and jumped to
directly without having to have a filesystem wrapper.
- Add a member to the struct added above to track the remote inode
length as that may differ if local modifications are buffered. We
may need to supply an appropriate EOF pointer when storing data (in
AFS for example).
- Pass extra information to netfs_alloc_request() so that the
->init_request() hook can access it and retain information to
indicate the origin of the operation.
- Make the ->init_request() hook return an error, thereby allowing a
filesystem that isn't allowed to cache an inode (ceph or cifs, for
example) to skip readahead.
- Switch to using refcount_t for subrequests and add tracepoints to
log refcount changes for the request and subrequest structs.
- Add a function to consolidate dispatching a read request. Similar
code is used in three places and another couple are likely to be
added in the future"
Link: https://lore.kernel.org/all/2639515.1648483225@warthog.procyon.org.uk/
* tag 'netfs-prep-20220318' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: Maintain netfs_i_context::remote_i_size
netfs: Keep track of the actual remote file size
netfs: Split some core bits out into their own file
netfs: Split fs/netfs/read_helper.c
netfs: Rename read_helper.c to io.c
netfs: Prepare to split read_helper.c
netfs: Add a function to consolidate beginning a read
netfs: Add a netfs inode context
ceph: Make ceph_init_request() check caps on readahead
netfs: Change ->init_request() to return an error code
netfs: Refactor arguments for netfs_alloc_read_request
netfs: Adjust the netfs_failure tracepoint to indicate non-subreq lines
netfs: Trace refcounting on the netfs_io_subrequest struct
netfs: Trace refcounting on the netfs_io_request struct
netfs: Adjust the netfs_rreq tracepoint slightly
netfs: Split netfs_io_* object handling out
netfs: Finish off rename of netfs_read_request to netfs_io_request
netfs: Rename netfs_read_*request to netfs_io_*request
netfs: Generate enums from trace symbol mapping lists
fscache: export fscache_end_operation()
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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 <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
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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A network filesystem may set coherency data on a volume cookie, and if
given, cachefiles will store this in an xattr on the directory in the
cache corresponding to the volume.
The function that sets the xattr just stores the contents of the volume
coherency buffer directly into the xattr, with nothing added; the
checking function, on the other hand, has a cut'n'paste error whereby it
tries to interpret the xattr contents as would be the xattr on an
ordinary file (using the cachefiles_xattr struct). This results in a
failure to match the coherency data because the buffer ends up being
shifted by 18 bytes.
Fix this by defining a structure specifically for the volume xattr and
making both the setting and checking functions use it.
Since the volume coherency doesn't work if used, take the opportunity to
insert a reserved field for future use, set it to 0 and check that it is
0. Log mismatch through the appropriate tracepoint.
Note that this only affects cifs; 9p, afs, ceph and nfs don't use the
volume coherency data at the moment.
Fixes: 32e150037dce ("fscache, cachefiles: Store the volume coherency data")
Reported-by: Rohith Surabattula <rohiths.msft@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Steve French <smfrench@gmail.com>
cc: linux-cifs@vger.kernel.org
cc: linux-cachefs@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a tracepoint to log failure to apply an active mark to a file in
addition to tracing successfully setting and unsetting the mark.
Also include the backing file inode number in the message logged to dmesg.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/164251404666.3435901.17331742792401482190.stgit@warthog.procyon.org.uk/ # v1
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Make some adjustments to tracepoints to make the tracing a bit more
followable:
(1) Standardise on displaying the backing inode number as "B=<hex>" with
no leading zeros.
(2) Make the cachefiles_lookup tracepoint log the directory inode number
as well as the looked-up inode number.
(3) Add a cachefiles_lookup tracepoint into cachefiles_get_directory() to
log directory lookup.
(4) Add a new cachefiles_mkdir tracepoint and use that to log a successful
mkdir from cachefiles_get_directory().
(5) Make the cachefiles_unlink and cachefiles_rename tracepoints log the
inode number of the affected file/dir rather than dentry struct
pointers.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/164251403694.3435901.9797725381831316715.stgit@warthog.procyon.org.uk/ # v1
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Store the volume coherency data in an xattr and check it when we rebind the
volume. If it doesn't match the cache volume is moved to the graveyard and
rebuilt anew.
Changes
=======
ver #4:
- Remove a couple of debugging prints.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/163967164397.1823006.2950539849831291830.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021563138.640689.15851092065380543119.stgit@warthog.procyon.org.uk/ # v4
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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 <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
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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Use an xattr on each backing file in the cache to store some metadata, such
as the content type and the coherency data.
Five content types are defined:
(0) No content stored.
(1) The file contains a single monolithic blob and must be all or nothing.
This would be used for something like an AFS directory or a symlink.
(2) The file is populated with content completely up to a point with
nothing beyond that.
(3) The file has a map attached and is sparsely populated. This would be
stored in one or more additional xattrs.
(4) The file is dirty, being in the process of local modification and the
contents are not necessarily represented correctly by the metadata.
The file should be deleted if this is seen on binding.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819641320.215744.16346770087799536862.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906942248.143852.5423738045012094252.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967151734.1823006.9301249989443622576.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021550471.640689.553853918307994335.stgit@warthog.procyon.org.uk/ # v4
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Implement allocate, get, see and put functions for the cachefiles_object
struct. The members of the struct we're going to need are also added.
Additionally, implement a lifecycle tracepoint.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819639457.215744.4600093239395728232.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906939569.143852.3594314410666551982.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967148857.1823006.6332962598220464364.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021547762.640689.8422781599594931000.stgit@warthog.procyon.org.uk/ # v4
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Add tracepoints in cachefiles to monitor when it does various VFS
operations, such as mkdir.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819638517.215744.12773133137536579766.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906938316.143852.17227990869551737803.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967147139.1823006.4909879317496543392.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021546287.640689.3501604495002415631.stgit@warthog.procyon.org.uk/ # v4
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Use an inode flag, S_KERNEL_FILE, to mark that a backing file is in use by
the kernel to prevent cachefiles or other kernel services from interfering
with that file.
Alter rmdir to reject attempts to remove a directory marked with this flag.
This is used by cachefiles to prevent cachefilesd from removing them.
Using S_SWAPFILE instead isn't really viable as that has other effects in
the I/O paths.
Changes
=======
ver #3:
- Check for the object pointer being NULL in the tracepoints rather than
the caller.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819630256.215744.4815885535039369574.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906931596.143852.8642051223094013028.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967141000.1823006.12920680657559677789.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021541207.640689.564689725898537127.stgit@warthog.procyon.org.uk/ # v4
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Add two trace points to log errors, one for vfs operations like mkdir or
create, and one for I/O operations, like read, write or truncate.
Also add the beginnings of a struct that is going to represent a data file
and place a debugging ID in it for the tracepoints to record.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819625632.215744.17907340966178411033.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906926297.143852.18267924605548658911.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967135390.1823006.2512120406360156424.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021534029.640689.1875723624947577095.stgit@warthog.procyon.org.uk/ # v4
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Introduce basic skeleton of the rewritten cachefiles driver including
config options so that it can be enabled for compilation.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819622766.215744.9108359326983195047.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906923341.143852.3856498104256721447.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967130320.1823006.15791456613198441566.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021528993.640689.9069695476048171884.stgit@warthog.procyon.org.uk/ # v4
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Delete the code from the cachefiles driver to make it easier to rewrite and
resubmit in a logical manner.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819577641.215744.12718114397770666596.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906883770.143852.4149714614981373410.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967076066.1823006.7175712134577687753.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021483619.640689.7586546280515844702.stgit@warthog.procyon.org.uk/ # v4
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When cachefiles_cull() calls cachefiles_bury_object(), it passes
a NULL object. When this occurs, either trace_cachefiles_unlink()
or trace_cachefiles_rename() may oops due to the NULL object.
Check for NULL object in the tracepoint and if so, set debug_id
to MAX_UINT as was done in 2908f5e101e3.
The following oops was seen with xfstests generic/100.
BUG: kernel NULL pointer dereference, address: 0000000000000010
...
RIP: 0010:trace_event_raw_event_cachefiles_unlink+0x4e/0xa0 [cachefiles]
...
Call Trace:
cachefiles_bury_object+0x242/0x430 [cachefiles]
? __vfs_removexattr_locked+0x10f/0x150
? vfs_removexattr+0x51/0xd0
cachefiles_cull+0x84/0x120 [cachefiles]
cachefiles_daemon_cull+0xd1/0x120 [cachefiles]
cachefiles_daemon_write+0x158/0x190 [cachefiles]
vfs_write+0xbc/0x260
ksys_write+0x4f/0xc0
do_syscall_64+0x3b/0x90
The following oops was seen with xfstests generic/290.
BUG: kernel NULL pointer dereference, address: 0000000000000010
...
RIP: 0010:trace_event_raw_event_cachefiles_rename+0x54/0xa0 [cachefiles]
...
Call Trace:
cachefiles_bury_object+0x35c/0x430 [cachefiles]
cachefiles_cull+0x84/0x120 [cachefiles]
cachefiles_daemon_cull+0xd1/0x120 [cachefiles]
cachefiles_daemon_write+0x158/0x190 [cachefiles]
vfs_write+0xbc/0x260
ksys_write+0x4f/0xc0
do_syscall_64+0x3b/0x90
Fixes: 2908f5e101e3 ("fscache: Add a cookie debug ID and use that in traces")
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://listman.redhat.com/archives/linux-cachefs/2021-October/msg00009.html
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In cachefiles_mark_object_buried, the dentry in question may not have an
owner, and thus our cachefiles_object pointer may be NULL when calling
the tracepoint, in which case we will also not have a valid debug_id to
print in the tracepoint.
Check for NULL object in the tracepoint and if so, just set debug_id to
MAX_UINT as was done in 2908f5e101e3 ("fscache: Add a cookie debug ID
and use that in traces").
This fixes the following oops:
FS-Cache: Cache "mycache" added (type cachefiles)
CacheFiles: File cache on vdc registered
...
Workqueue: fscache_object fscache_object_work_func [fscache]
RIP: 0010:trace_event_raw_event_cachefiles_mark_buried+0x4e/0xa0 [cachefiles]
....
Call Trace:
cachefiles_mark_object_buried+0xa5/0xb0 [cachefiles]
cachefiles_bury_object+0x270/0x430 [cachefiles]
cachefiles_walk_to_object+0x195/0x9c0 [cachefiles]
cachefiles_lookup_object+0x5a/0xc0 [cachefiles]
fscache_look_up_object+0xd7/0x160 [fscache]
fscache_object_work_func+0xb2/0x340 [fscache]
process_one_work+0x1f1/0x390
worker_thread+0x53/0x3e0
kthread+0x127/0x150
Fixes: 2908f5e101e3 ("fscache: Add a cookie debug ID and use that in traces")
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a cookie debug ID and use that in traces and in procfiles rather than
displaying the (hashed) pointer to the cookie. This is easier to correlate
and we don't lose anything when interpreting oops output since that shows
unhashed addresses and registers that aren't comparable to the hashed
values.
Changes:
ver #2:
- Fix the fscache_op tracepoint to handle a NULL cookie pointer.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/158861210988.340223.11688464116498247790.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/159465769844.1376105.14119502774019865432.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/160588459097.3465195.1273313637721852165.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/162431193544.2908479.17556704572948300790.stgit@warthog.procyon.org.uk/
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Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public licence as published by
the free software foundation either version 2 of the licence or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 114 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add some tracepoints to fscache:
(*) fscache_cookie - Tracks a cookie's usage count.
(*) fscache_netfs - Logs registration of a network filesystem, including
the pointer to the cookie allocated.
(*) fscache_acquire - Logs cookie acquisition.
(*) fscache_relinquish - Logs cookie relinquishment.
(*) fscache_enable - Logs enablement of a cookie.
(*) fscache_disable - Logs disablement of a cookie.
(*) fscache_osm - Tracks execution of states in the object state machine.
and cachefiles:
(*) cachefiles_ref - Tracks a cachefiles object's usage count.
(*) cachefiles_lookup - Logs result of lookup_one_len().
(*) cachefiles_mkdir - Logs result of vfs_mkdir().
(*) cachefiles_create - Logs result of vfs_create().
(*) cachefiles_unlink - Logs calls to vfs_unlink().
(*) cachefiles_rename - Logs calls to vfs_rename().
(*) cachefiles_mark_active - Logs an object becoming active.
(*) cachefiles_wait_active - Logs a wait for an old object to be
destroyed.
(*) cachefiles_mark_inactive - Logs an object becoming inactive.
(*) cachefiles_mark_buried - Logs the burial of an object.
Signed-off-by: David Howells <dhowells@redhat.com>
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