| Age | Commit message (Collapse) | Author |
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If ->readpage returns an error, it has already unlocked the page.
Fixes: 5e929b33c393 ("CacheFiles: Handle truncate unlocking the page we're reading")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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__kernel_write doesn't take a sb_writers references, which we need here.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
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There is a potential race in fscache operation enqueuing for reading and
copying multiple pages from cachefiles to netfs. The problem can be seen
easily on a heavy loaded system (for example many processes reading files
continually on an NFS share covered by fscache triggered this problem within
a few minutes).
The race is due to cachefiles_read_waiter() adding the op to the monitor
to_do list and then then drop the object->work_lock spinlock before
completing fscache_enqueue_operation(). Once the lock is dropped,
cachefiles_read_copier() grabs the op, completes processing it, and
makes it through fscache_retrieval_complete() which sets the op->state to
the final state of FSCACHE_OP_ST_COMPLETE(4). When cachefiles_read_waiter()
finally gets through the remainder of fscache_enqueue_operation()
it sees the invalid state, and hits the ASSERTCMP and the following
oops is seen:
[ 2259.612361] FS-Cache:
[ 2259.614785] FS-Cache: Assertion failed
[ 2259.618639] FS-Cache: 4 == 5 is false
[ 2259.622456] ------------[ cut here ]------------
[ 2259.627190] kernel BUG at fs/fscache/operation.c:70!
...
[ 2259.791675] RIP: 0010:[<ffffffffc061b4cf>] [<ffffffffc061b4cf>] fscache_enqueue_operation+0xff/0x170 [fscache]
[ 2259.802059] RSP: 0000:ffffa0263d543be0 EFLAGS: 00010046
[ 2259.807521] RAX: 0000000000000019 RBX: ffffa01a4d390480 RCX: 0000000000000006
[ 2259.814847] RDX: 0000000000000000 RSI: 0000000000000046 RDI: ffffa0263d553890
[ 2259.822176] RBP: ffffa0263d543be8 R08: 0000000000000000 R09: ffffa0263c2d8708
[ 2259.829502] R10: 0000000000001e7f R11: 0000000000000000 R12: ffffa01a4d390480
[ 2259.844483] R13: ffff9fa9546c5920 R14: ffffa0263d543c80 R15: ffffa0293ff9bf10
[ 2259.859554] FS: 00007f4b6efbd700(0000) GS:ffffa0263d540000(0000) knlGS:0000000000000000
[ 2259.875571] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2259.889117] CR2: 00007f49e1624ff0 CR3: 0000012b38b38000 CR4: 00000000007607e0
[ 2259.904015] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 2259.918764] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 2259.933449] PKRU: 55555554
[ 2259.943654] Call Trace:
[ 2259.953592] <IRQ>
[ 2259.955577] [<ffffffffc03a7c12>] cachefiles_read_waiter+0x92/0xf0 [cachefiles]
[ 2259.978039] [<ffffffffa34d3942>] __wake_up_common+0x82/0x120
[ 2259.991392] [<ffffffffa34d3a63>] __wake_up_common_lock+0x83/0xc0
[ 2260.004930] [<ffffffffa34d3510>] ? task_rq_unlock+0x20/0x20
[ 2260.017863] [<ffffffffa34d3ab3>] __wake_up+0x13/0x20
[ 2260.030230] [<ffffffffa34c72a0>] __wake_up_bit+0x50/0x70
[ 2260.042535] [<ffffffffa35bdcdb>] unlock_page+0x2b/0x30
[ 2260.054495] [<ffffffffa35bdd09>] page_endio+0x29/0x90
[ 2260.066184] [<ffffffffa368fc81>] mpage_end_io+0x51/0x80
CPU1
cachefiles_read_waiter()
20 static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode,
21 int sync, void *_key)
22 {
...
61 spin_lock(&object->work_lock);
62 list_add_tail(&monitor->op_link, &op->to_do);
63 spin_unlock(&object->work_lock);
<begin race window>
64
65 fscache_enqueue_retrieval(op);
182 static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op)
183 {
184 fscache_enqueue_operation(&op->op);
185 }
58 void fscache_enqueue_operation(struct fscache_operation *op)
59 {
60 struct fscache_cookie *cookie = op->object->cookie;
61
62 _enter("{OBJ%x OP%x,%u}",
63 op->object->debug_id, op->debug_id, atomic_read(&op->usage));
64
65 ASSERT(list_empty(&op->pend_link));
66 ASSERT(op->processor != NULL);
67 ASSERT(fscache_object_is_available(op->object));
68 ASSERTCMP(atomic_read(&op->usage), >, 0);
<end race window>
CPU2
cachefiles_read_copier()
168 while (!list_empty(&op->to_do)) {
...
202 fscache_end_io(op, monitor->netfs_page, error);
203 put_page(monitor->netfs_page);
204 fscache_retrieval_complete(op, 1);
CPU1
58 void fscache_enqueue_operation(struct fscache_operation *op)
59 {
...
69 ASSERTIFCMP(op->state != FSCACHE_OP_ST_IN_PROGRESS,
70 op->state, ==, FSCACHE_OP_ST_CANCELLED);
Signed-off-by: Lei Xue <carmark.dlut@gmail.com>
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
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cachefiles_read_or_alloc_pages()
The patch which changed cachefiles from calling ->bmap() to using the
bmap() wrapper overwrote the running return value with the result of
calling bmap(). This causes an assertion failure elsewhere in the code.
Fix this by using ret2 rather than ret to hold the return value.
The oops looks like:
kernel BUG at fs/nfs/fscache.c:468!
...
RIP: 0010:__nfs_readpages_from_fscache+0x18b/0x190 [nfs]
...
Call Trace:
nfs_readpages+0xbf/0x1c0 [nfs]
? __alloc_pages_nodemask+0x16c/0x320
read_pages+0x67/0x1a0
__do_page_cache_readahead+0x1cf/0x1f0
ondemand_readahead+0x172/0x2b0
page_cache_async_readahead+0xaa/0xe0
generic_file_buffered_read+0x852/0xd50
? mem_cgroup_commit_charge+0x6e/0x140
? nfs4_have_delegation+0x19/0x30 [nfsv4]
generic_file_read_iter+0x100/0x140
? nfs_revalidate_mapping+0x176/0x2b0 [nfs]
nfs_file_read+0x6d/0xc0 [nfs]
new_sync_read+0x11a/0x1c0
__vfs_read+0x29/0x40
vfs_read+0x8e/0x140
ksys_read+0x61/0xd0
__x64_sys_read+0x1a/0x20
do_syscall_64+0x60/0x1e0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f5d148267e0
Fixes: 10d83e11a582 ("cachefiles: drop direct usage of ->bmap method.")
Reported-by: David Wysochanski <dwysocha@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: David Wysochanski <dwysocha@redhat.com>
cc: Carlos Maiolino <cmaiolino@redhat.com>
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Replace the direct usage of ->bmap method by a bmap() call.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.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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Variable 'cache' is being assigned but is never used hence it is
redundant and can be removed.
Cleans up clang warning:
warning: variable 'cache' set but not used [-Wunused-but-set-variable]
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David Howells <dhowells@redhat.com>
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[Description]
In a heavily loaded system where the system pagecache is nearing memory
limits and fscache is enabled, pages can be leaked by fscache while trying
read pages from cachefiles backend. This can happen because two
applications can be reading same page from a single mount, two threads can
be trying to read the backing page at same time. This results in one of
the threads finding that a page for the backing file or netfs file is
already in the radix tree. During the error handling cachefiles does not
clean up the reference on backing page, leading to page leak.
[Fix]
The fix is straightforward, to decrement the reference when error is
encountered.
[dhowells: Note that I've removed the clearance and put of newpage as
they aren't attested in the commit message and don't appear to actually
achieve anything since a new page is only allocated is newpage!=NULL and
any residual new page is cleared before returning.]
[Testing]
I have tested the fix using following method for 12+ hrs.
1) mkdir -p /mnt/nfs ; mount -o vers=3,fsc <server_ip>:/export /mnt/nfs
2) create 10000 files of 2.8MB in a NFS mount.
3) start a thread to simulate heavy VM presssure
(while true ; do echo 3 > /proc/sys/vm/drop_caches ; sleep 1 ; done)&
4) start multiple parallel reader for data set at same time
find /mnt/nfs -type f | xargs -P 80 cat > /dev/null &
find /mnt/nfs -type f | xargs -P 80 cat > /dev/null &
find /mnt/nfs -type f | xargs -P 80 cat > /dev/null &
..
..
find /mnt/nfs -type f | xargs -P 80 cat > /dev/null &
find /mnt/nfs -type f | xargs -P 80 cat > /dev/null &
5) finally check using cat /proc/fs/fscache/stats | grep -i pages ;
free -h , cat /proc/meminfo and page-types -r -b lru
to ensure all pages are freed.
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Kiran Kumar Modukuri <kiran.modukuri@gmail.com>
[dja: forward ported to current upstream]
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: David Howells <dhowells@redhat.com>
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cachefiles_read_waiter() has the right to access a 'monitor' object by
virtue of being called under the waitqueue lock for one of the pages in its
purview. However, it has no ref on that monitor object or on the
associated operation.
What it is allowed to do is to move the monitor object to the operation's
to_do list, but once it drops the work_lock, it's actually no longer
permitted to access that object. However, it is trying to enqueue the
retrieval operation for processing - but it can only do this via a pointer
in the monitor object, something it shouldn't be doing.
If it doesn't enqueue the operation, the operation may not get processed.
If the order is flipped so that the enqueue is first, then it's possible
for the work processor to look at the to_do list before the monitor is
enqueued upon it.
Fix this by getting a ref on the operation so that we can trust that it
will still be there once we've added the monitor to the to_do list and
dropped the work_lock. The op can then be enqueued after the lock is
dropped.
The bug can manifest in one of a couple of ways. The first manifestation
looks like:
FS-Cache:
FS-Cache: Assertion failed
FS-Cache: 6 == 5 is false
------------[ cut here ]------------
kernel BUG at fs/fscache/operation.c:494!
RIP: 0010:fscache_put_operation+0x1e3/0x1f0
...
fscache_op_work_func+0x26/0x50
process_one_work+0x131/0x290
worker_thread+0x45/0x360
kthread+0xf8/0x130
? create_worker+0x190/0x190
? kthread_cancel_work_sync+0x10/0x10
ret_from_fork+0x1f/0x30
This is due to the operation being in the DEAD state (6) rather than
INITIALISED, COMPLETE or CANCELLED (5) because it's already passed through
fscache_put_operation().
The bug can also manifest like the following:
kernel BUG at fs/fscache/operation.c:69!
...
[exception RIP: fscache_enqueue_operation+246]
...
#7 [ffff883fff083c10] fscache_enqueue_operation at ffffffffa0b793c6
#8 [ffff883fff083c28] cachefiles_read_waiter at ffffffffa0b15a48
#9 [ffff883fff083c48] __wake_up_common at ffffffff810af028
I'm not entirely certain as to which is line 69 in Lei's kernel, so I'm not
entirely clear which assertion failed.
Fixes: 9ae326a69004 ("CacheFiles: A cache that backs onto a mounted filesystem")
Reported-by: Lei Xue <carmark.dlut@gmail.com>
Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Reported-by: Anthony DeRobertis <aderobertis@metrics.net>
Reported-by: NeilBrown <neilb@suse.com>
Reported-by: Daniel Axtens <dja@axtens.net>
Reported-by: Kiran Kumar Modukuri <kiran.modukuri@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
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Fix a couple of checker warnings in fscache and cachefiles:
(1) fscache_n_op_requeue is never used, so get rid of it.
(2) cachefiles_uncache_page() is passed in a lock that it releases, so
this needs annotating.
Signed-off-by: David Howells <dhowells@redhat.com>
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As the page free path makes no distinction between cache hot and cold
pages, there is no real useful ordering of pages in the free list that
allocation requests can take advantage of. Juding from the users of
__GFP_COLD, it is likely that a number of them are the result of copying
other sites instead of actually measuring the impact. Remove the
__GFP_COLD parameter which simplifies a number of paths in the page
allocator.
This is potentially controversial but bear in mind that the size of the
per-cpu pagelists versus modern cache sizes means that the whole per-cpu
list can often fit in the L3 cache. Hence, there is only a potential
benefit for microbenchmarks that alloc/free pages in a tight loop. It's
even worse when THP is taken into account which has little or no chance
of getting a cache-hot page as the per-cpu list is bypassed and the
zeroing of multiple pages will thrash the cache anyway.
The truncate microbenchmarks are not shown as this patch affects the
allocation path and not the free path. A page fault microbenchmark was
tested but it showed no sigificant difference which is not surprising
given that the __GFP_COLD branches are a miniscule percentage of the
fault path.
Link: http://lkml.kernel.org/r/20171018075952.10627-9-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Every pagevec_init user claims the pages being released are hot even in
cases where it is unlikely the pages are hot. As no one cares about the
hotness of pages being released to the allocator, just ditch the
parameter.
No performance impact is expected as the overhead is marginal. The
parameter is removed simply because it is a bit stupid to have a useless
parameter copied everywhere.
Link: http://lkml.kernel.org/r/20171018075952.10627-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.
Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.
To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:
struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entry
For example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {
... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:
list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fs/cachefiles/rdwr.c: In function ‘cachefiles_write_page’:
fs/cachefiles/rdwr.c:882: warning: ‘ret’ may be used uninitialized in
this function
If the jump to label "error" is taken, "ret" will indeed be
uninitialized, and random stack data may be printed by the debug code.
Fixes: 102f4d900c9c8f5e ("FS-Cache: Handle a write to the page immediately beyond the EOF marker")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Handle a write being requested to the page immediately beyond the EOF
marker on a cache object. Currently this gets an assertion failure in
CacheFiles because the EOF marker is used there to encode information about
a partial page at the EOF - which could lead to an unknown blank spot in
the file if we extend the file over it.
The problem is actually in fscache where we check the index of the page
being written against store_limit. store_limit is set to the number of
pages that we're allowed to store by fscache_set_store_limit() - which
means it's one more than the index of the last page we're allowed to store.
The problem is that we permit writing to a page with an index _equal_ to
the store limit - when we should reject that case.
Whilst we're at it, change the triggered assertion in CacheFiles to just
return -ENOBUFS instead.
The assertion failure looks something like this:
CacheFiles: Assertion failed
1000 < 7b1 is false
------------[ cut here ]------------
kernel BUG at fs/cachefiles/rdwr.c:962!
...
RIP: 0010:[<ffffffffa02c9e83>] [<ffffffffa02c9e83>] cachefiles_write_page+0x273/0x2d0 [cachefiles]
Cc: stable@vger.kernel.org # v2.6.31+; earlier - that + backport of a17754f (at least)
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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cachefiles requires that s_blocksize in the cache is not greater than
PAGE_SIZE, and performs the check every time a block is accessed.
Move the test to the place where the file is "opened", where other
file-validity tests are performed.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Fix up the following scripted S_ISDIR/S_ISREG/S_ISLNK conversions (or lack
thereof) in cachefiles:
(1) Cachefiles mostly wants to use d_can_lookup() rather than d_is_dir() as
it doesn't want to deal with automounts in its cache.
(2) Coccinelle didn't find S_IS* expressions in ASSERT() statements in
cachefiles.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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These two have been unused since
commit c4d6d8dbf335c7fa47341654a37c53a512b519bb
CacheFiles: Fix the marking of cached pages
in 3.8.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: David Howells <dhowells@redhat.com>
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This code used to have its own lru cache pagevec up until a0b8cab3 ("mm:
remove lru parameter from __pagevec_lru_add and remove parts of pagevec
API"). Now it's just add_to_page_cache() followed by lru_cache_add(),
might as well use add_to_page_cache_lru() directly.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Metin Doslu <metin@citusdata.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ozgun Erdogan <ozgun@citusdata.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Now that the LRU to add a page to is decided at LRU-add time, remove the
misleading lru parameter from __pagevec_lru_add. A consequence of this
is that the pagevec_lru_add_file, pagevec_lru_add_anon and similar
helpers are misleading as the caller no longer has direct control over
what LRU the page is added to. Unused helpers are removed by this patch
and existing users of pagevec_lru_add_file() are converted to use
lru_cache_add_file() directly and use the per-cpu pagevecs instead of
creating their own pagevec.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com>
Cc: Andrew Perepechko <anserper@ya.ru>
Cc: Robin Dong <sanbai@taobao.com>
Cc: Theodore Tso <tytso@mit.edu>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
|
CacheFiles is missing some calls to fscache_retrieval_complete() in the error
handling/collision paths of its reader functions.
This can be seen by the following assertion tripping in fscache_put_operation()
whereby the operation being destroyed is still in the in-progress state and has
not been cancelled or completed:
FS-Cache: Assertion failed
3 == 5 is false
------------[ cut here ]------------
kernel BUG at fs/fscache/operation.c:408!
invalid opcode: 0000 [#1] SMP
CPU 2
Modules linked in: xfs ioatdma dca loop joydev evdev
psmouse dcdbas pcspkr serio_raw i5000_edac edac_core i5k_amb shpchp
pci_hotplug sg sr_mod]
Pid: 8062, comm: httpd Not tainted 3.1.0-rc8 #1 Dell Inc. PowerEdge 1950/0DT097
RIP: 0010:[<ffffffff81197b24>] [<ffffffff81197b24>] fscache_put_operation+0x304/0x330
RSP: 0018:ffff880062f739d8 EFLAGS: 00010296
RAX: 0000000000000025 RBX: ffff8800c5122e84 RCX: ffffffff81ddf040
RDX: 00000000ffffffff RSI: 0000000000000082 RDI: ffffffff81ddef30
RBP: ffff880062f739f8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000003 R12: ffff8800c5122e40
R13: ffff880037a2cd20 R14: ffff880087c7a058 R15: ffff880087c7a000
FS: 00007f63dcf636e0(0000) GS:ffff88022fc80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0c0a91f000 CR3: 0000000062ec2000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process httpd (pid: 8062, threadinfo ffff880062f72000, task ffff880087e58000)
Stack:
ffff880062f73bf8 0000000000000000 ffff880062f73bf8 ffff880037a2cd20
ffff880062f73a68 ffffffff8119aa7e ffff88006540e000 ffff880062f73ad4
ffff88008e9a4308 ffff880037a2cd20 ffff880062f73a48 ffff8800c5122e40
Call Trace:
[<ffffffff8119aa7e>] __fscache_read_or_alloc_pages+0x1fe/0x530
[<ffffffff81250780>] __nfs_readpages_from_fscache+0x70/0x1c0
[<ffffffff8123142a>] nfs_readpages+0xca/0x1e0
[<ffffffff815f3c06>] ? rpc_do_put_task+0x36/0x50
[<ffffffff8122755b>] ? alloc_nfs_open_context+0x4b/0x110
[<ffffffff815ecd1a>] ? rpc_call_sync+0x5a/0x70
[<ffffffff810e7e9a>] __do_page_cache_readahead+0x1ca/0x270
[<ffffffff810e7f61>] ra_submit+0x21/0x30
[<ffffffff810e818d>] ondemand_readahead+0x11d/0x250
[<ffffffff810e83b6>] page_cache_sync_readahead+0x36/0x60
[<ffffffff810dffa4>] generic_file_aio_read+0x454/0x770
[<ffffffff81224ce1>] nfs_file_read+0xe1/0x130
[<ffffffff81121bd9>] do_sync_read+0xd9/0x120
[<ffffffff8114088f>] ? mntput+0x1f/0x40
[<ffffffff811238cb>] ? fput+0x1cb/0x260
[<ffffffff81122938>] vfs_read+0xc8/0x180
[<ffffffff81122af5>] sys_read+0x55/0x90
Reported-by: Mark Moseley <moseleymark@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Implement invalidation for CacheFiles. This is in two parts:
(1) Provide an invalidation method (which just truncates the backing file).
(2) Abort attempts to copy anything read from the backing file whilst
invalidation is in progress.
Question: CacheFiles uses truncation in a couple of places. It has been using
notify_change() rather than sys_truncate() or something similar. This means
it bypasses a bunch of checks and suchlike that it possibly should be making
(security, file locking, lease breaking, vfsmount write). Should it be using
vfs_truncate() as added by a preceding patch or should it use notify_write()
and assume that anyone poking around in the cache files on disk gets
everything they deserve?
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Fix the state management of internal fscache operations and the accounting of
what operations are in what states.
This is done by:
(1) Give struct fscache_operation a enum variable that directly represents the
state it's currently in, rather than spreading this knowledge over a bunch
of flags, who's processing the operation at the moment and whether it is
queued or not.
This makes it easier to write assertions to check the state at various
points and to prevent invalid state transitions.
(2) Add an 'operation complete' state and supply a function to indicate the
completion of an operation (fscache_op_complete()) and make things call
it. The final call to fscache_put_operation() can then check that an op
in the appropriate state (complete or cancelled).
(3) Adjust the use of object->n_ops, ->n_in_progress, ->n_exclusive to better
govern the state of an object:
(a) The ->n_ops is now the number of extant operations on the object
and is now decremented by fscache_put_operation() only.
(b) The ->n_in_progress is simply the number of objects that have been
taken off of the object's pending queue for the purposes of being
run. This is decremented by fscache_op_complete() only.
(c) The ->n_exclusive is the number of exclusive ops that have been
submitted and queued or are in progress. It is decremented by
fscache_op_complete() and by fscache_cancel_op().
fscache_put_operation() and fscache_operation_gc() now no longer try to
clean up ->n_exclusive and ->n_in_progress. That was leading to double
decrements against fscache_cancel_op().
fscache_cancel_op() now no longer decrements ->n_ops. That was leading to
double decrements against fscache_put_operation().
fscache_submit_exclusive_op() now decides whether it has to queue an op
based on ->n_in_progress being > 0 rather than ->n_ops > 0 as the latter
will persist in being true even after all preceding operations have been
cancelled or completed. Furthermore, if an object is active and there are
runnable ops against it, there must be at least one op running.
(4) Add a remaining-pages counter (n_pages) to struct fscache_retrieval and
provide a function to record completion of the pages as they complete.
When n_pages reaches 0, the operation is deemed to be complete and
fscache_op_complete() is called.
Add calls to fscache_retrieval_complete() anywhere we've finished with a
page we've been given to read or allocate for. This includes places where
we just return pages to the netfs for reading from the server and where
accessing the cache fails and we discard the proposed netfs page.
The bugs in the unfixed state management manifest themselves as oopses like the
following where the operation completion gets out of sync with return of the
cookie by the netfs. This is possible because the cache unlocks and returns
all the netfs pages before recording its completion - which means that there's
nothing to stop the netfs discarding them and returning the cookie.
FS-Cache: Cookie 'NFS.fh' still has outstanding reads
------------[ cut here ]------------
kernel BUG at fs/fscache/cookie.c:519!
invalid opcode: 0000 [#1] SMP
CPU 1
Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc
Pid: 400, comm: kswapd0 Not tainted 3.1.0-rc7-fsdevel+ #1090 /DG965RY
RIP: 0010:[<ffffffffa007050a>] [<ffffffffa007050a>] __fscache_relinquish_cookie+0x170/0x343 [fscache]
RSP: 0018:ffff8800368cfb00 EFLAGS: 00010282
RAX: 000000000000003c RBX: ffff880023cc8790 RCX: 0000000000000000
RDX: 0000000000002f2e RSI: 0000000000000001 RDI: ffffffff813ab86c
RBP: ffff8800368cfb50 R08: 0000000000000002 R09: 0000000000000000
R10: ffff88003a1b7890 R11: ffff88001df6e488 R12: ffff880023d8ed98
R13: ffff880023cc8798 R14: 0000000000000004 R15: ffff88003b8bf370
FS: 0000000000000000(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000008ba008 CR3: 0000000023d93000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process kswapd0 (pid: 400, threadinfo ffff8800368ce000, task ffff88003b8bf040)
Stack:
ffff88003b8bf040 ffff88001df6e528 ffff88001df6e528 ffffffffa00b46b0
ffff88003b8bf040 ffff88001df6e488 ffff88001df6e620 ffffffffa00b46b0
ffff88001ebd04c8 0000000000000004 ffff8800368cfb70 ffffffffa00b2c91
Call Trace:
[<ffffffffa00b2c91>] nfs_fscache_release_inode_cookie+0x3b/0x47 [nfs]
[<ffffffffa008f25f>] nfs_clear_inode+0x3c/0x41 [nfs]
[<ffffffffa0090df1>] nfs4_evict_inode+0x2f/0x33 [nfs]
[<ffffffff810d8d47>] evict+0xa1/0x15c
[<ffffffff810d8e2e>] dispose_list+0x2c/0x38
[<ffffffff810d9ebd>] prune_icache_sb+0x28c/0x29b
[<ffffffff810c56b7>] prune_super+0xd5/0x140
[<ffffffff8109b615>] shrink_slab+0x102/0x1ab
[<ffffffff8109d690>] balance_pgdat+0x2f2/0x595
[<ffffffff8103e009>] ? process_timeout+0xb/0xb
[<ffffffff8109dba3>] kswapd+0x270/0x289
[<ffffffff8104c5ea>] ? __init_waitqueue_head+0x46/0x46
[<ffffffff8109d933>] ? balance_pgdat+0x595/0x595
[<ffffffff8104bf7a>] kthread+0x7f/0x87
[<ffffffff813ad6b4>] kernel_thread_helper+0x4/0x10
[<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0
[<ffffffff813abcdd>] ? retint_restore_args+0xe/0xe
[<ffffffff8104befb>] ? __init_kthread_worker+0x53/0x53
[<ffffffff813ad6b0>] ? gs_change+0xb/0xb
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Downgrade some debugging statements to not unconditionally print stuff, but
rather be conditional on the appropriate module parameter setting.
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Downgrade the requirements passed to the allocator in the gfp flags parameter.
FS-Cache/CacheFiles can handle OOM conditions simply by aborting the attempt to
store an object or a page in the cache.
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Under some circumstances CacheFiles defers the marking of pages with PG_fscache
so that it can take advantage of pagevecs to reduce the number of calls to
fscache_mark_pages_cached() and the netfs's hook to keep track of this.
There are, however, two problems with this:
(1) It can lead to the PG_fscache mark being applied _after_ the page is set
PG_uptodate and unlocked (by the call to fscache_end_io()).
(2) CacheFiles's ref on the page is dropped immediately following
fscache_end_io() - and so may not still be held when the mark is applied.
This can lead to the page being passed back to the allocator before the
mark is applied.
Fix this by, where appropriate, marking the page before calling
fscache_end_io() and releasing the page. This means that we can't take
advantage of pagevecs and have to make a separate call for each page to the
marking routines.
The symptoms of this are Bad Page state errors cropping up under memory
pressure, for example:
BUG: Bad page state in process tar pfn:002da
page:ffffea0000009fb0 count:0 mapcount:0 mapping: (null) index:0x1447
page flags: 0x1000(private_2)
Pid: 4574, comm: tar Tainted: G W 3.1.0-rc4-fsdevel+ #1064
Call Trace:
[<ffffffff8109583c>] ? dump_page+0xb9/0xbe
[<ffffffff81095916>] bad_page+0xd5/0xea
[<ffffffff81095d82>] get_page_from_freelist+0x35b/0x46a
[<ffffffff810961f3>] __alloc_pages_nodemask+0x362/0x662
[<ffffffff810989da>] __do_page_cache_readahead+0x13a/0x267
[<ffffffff81098942>] ? __do_page_cache_readahead+0xa2/0x267
[<ffffffff81098d7b>] ra_submit+0x1c/0x20
[<ffffffff8109900a>] ondemand_readahead+0x28b/0x29a
[<ffffffff81098ee2>] ? ondemand_readahead+0x163/0x29a
[<ffffffff810990ce>] page_cache_sync_readahead+0x38/0x3a
[<ffffffff81091d8a>] generic_file_aio_read+0x2ab/0x67e
[<ffffffffa008cfbe>] nfs_file_read+0xa4/0xc9 [nfs]
[<ffffffff810c22c4>] do_sync_read+0xba/0xfa
[<ffffffff81177a47>] ? security_file_permission+0x7b/0x84
[<ffffffff810c25dd>] ? rw_verify_area+0xab/0xc8
[<ffffffff810c29a4>] vfs_read+0xaa/0x13a
[<ffffffff810c2a79>] sys_read+0x45/0x6c
[<ffffffff813ac37b>] system_call_fastpath+0x16/0x1b
As can be seen, PG_private_2 (== PG_fscache) is set in the page flags.
Instrumenting fscache_mark_pages_cached() to verify whether page->mapping was
set appropriately showed that sometimes it wasn't. This led to the discovery
that sometimes the page has apparently been reclaimed by the time the marker
got to see it.
Reported-by: M. Stevens <m@tippett.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
|
|
Support the caching of large files.
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=31182
Signed-off-by: Justin Lecher <jlec@gentoo.org>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.com>
Tested-by: Suresh Jayaraman <sjayaraman@suse.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
|
Make fscache operation to use only workqueue instead of combination of
workqueue and slow-work. FSCACHE_OP_SLOW is dropped and
FSCACHE_OP_FAST is renamed to FSCACHE_OP_ASYNC and uses newly added
fscache_op_wq workqueue to execute op->processor().
fscache_operation_init_slow() is dropped and fscache_operation_init()
now takes @processor argument directly.
* Unbound workqueue is used.
* fscache_retrieval_work() is no longer necessary as OP_ASYNC now does
the equivalent thing.
* sysctl fscache.operation_max_active added to control concurrency.
The default value is nr_cpus clamped between 2 and
WQ_UNBOUND_MAX_ACTIVE.
* debugfs support is dropped for now. Tracing API based debug
facility is planned to be added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Howells <dhowells@redhat.com>
|
|
implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
|
|
* do ima_get_count() in __dentry_open()
* stop doing that in followups
* move ima_path_check() to right after nameidata_to_filp()
* don't bump counters on it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
|
When IMA is active, using dentry_open without updating the
IMA counters will result in free/open imbalance errors when
fput is eventually called.
Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Handle truncate unlocking the page we're attempting to read from the backing
device before the read has completed.
This was causing reports like the following to occur:
Pid: 4765, comm: kslowd Not tainted 2.6.30.1 #1
Call Trace:
[<ffffffffa0331d7a>] ? cachefiles_read_waiter+0xd9/0x147 [cachefiles]
[<ffffffff804b74bd>] ? __wait_on_bit+0x60/0x6f
[<ffffffff8022bbbb>] ? __wake_up_common+0x3f/0x71
[<ffffffff8022cc32>] ? __wake_up+0x30/0x44
[<ffffffff8024a41f>] ? __wake_up_bit+0x28/0x2d
[<ffffffffa003a793>] ? ext3_truncate+0x4d7/0x8ed [ext3]
[<ffffffff80281f90>] ? pagevec_lookup+0x17/0x1f
[<ffffffff8028c2ff>] ? unmap_mapping_range+0x59/0x1ff
[<ffffffff8022cc32>] ? __wake_up+0x30/0x44
[<ffffffff8028e286>] ? vmtruncate+0xc2/0xe2
[<ffffffff802b82cf>] ? inode_setattr+0x22/0x10a
[<ffffffffa003baa5>] ? ext3_setattr+0x17b/0x1e6 [ext3]
[<ffffffff802b853d>] ? notify_change+0x186/0x2c9
[<ffffffffa032d9de>] ? cachefiles_attr_changed+0x133/0x1cd [cachefiles]
[<ffffffffa032df7f>] ? cachefiles_lookup_object+0xcf/0x12a [cachefiles]
[<ffffffffa0318165>] ? fscache_lookup_object+0x110/0x122 [fscache]
[<ffffffffa03188c3>] ? fscache_object_slow_work_execute+0x590/0x6bc
[fscache]
[<ffffffff80278f82>] ? slow_work_thread+0x285/0x43a
[<ffffffff8024a446>] ? autoremove_wake_function+0x0/0x2e
[<ffffffff80278cfd>] ? slow_work_thread+0x0/0x43a
[<ffffffff8024a317>] ? kthread+0x54/0x81
[<ffffffff8020c93a>] ? child_rip+0xa/0x20
[<ffffffff8024a2c3>] ? kthread+0x0/0x81
[<ffffffff8020c930>] ? child_rip+0x0/0x20
CacheFiles: I/O Error: Readpage failed on backing file 200000000000810
FS-Cache: Cache cachefiles stopped due to I/O error
Reported-by: Christian Kujau <lists@nerdbynature.de>
Reported-by: Takashi Iwai <tiwai@suse.de>
Reported-by: Duc Le Minh <duclm.vn@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
cachefiles_write_page() writes a full page to the backing file for the last
page of the netfs file, even if the netfs file's last page is only a partial
page.
This causes the EOF on the backing file to be extended beyond the EOF of the
netfs, and thus the backing file will be truncated by cachefiles_attr_changed()
called from cachefiles_lookup_object().
So we need to limit the write we make to the backing file on that last page
such that it doesn't push the EOF too far.
Also, if a backing file that has a partial page at the end is expanded, we
discard the partial page and refetch it on the basis that we then have a hole
in the file with invalid data, and should the power go out... A better way to
deal with this could be to record a note that the partial page contains invalid
data until the correct data is written into it.
This isn't a problem for netfs's that discard the whole backing file if the
file size changes (such as NFS).
Signed-off-by: David Howells <dhowells@redhat.com>
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