Commit Graph

94 Commits

Author SHA1 Message Date
Linus Torvalds
7572395767 Fix possible splice() mmap_sem deadlock
Nick Piggin points out that splice isn't being good about the mmap
semaphore: while two readers can nest inside each others, it does leave
a possible deadlock if a writer (ie a new mmap()) comes in during that
nesting.

Original "just move the locking" patch by Nick, replaced by one by me
based on an optimistic pagefault_disable().  And then Jens tested and
updated that patch.

Reported-by: Nick Piggin <npiggin@suse.de>
Tested-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-01 13:17:28 -07:00
Randy Dunlap
79685b8dee docbook: add pipes, other fixes
Fix some typos in pipe.c and splice.c.
Add pipes API to kernel-api.tmpl.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-27 08:08:51 +02:00
Jens Axboe
6a860c979b splice: fix bad unlock_page() in error case
If add_to_page_cache_lru() fails, the page will not be locked. But
splice jumps to an error path that does a page release and unlock,
causing a BUG() in unlock_page().

Fix this by adding one more label that just releases the page. This bug
was actually triggered on EL5 by gurudas pai <gurudas.pai@oracle.com>
using fio.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-20 09:07:01 -07:00
Rusty Russell
cf914a7d65 readahead: split ondemand readahead interface into two functions
Split ondemand readahead interface into two functions.  I think this makes it
a little clearer for non-readahead experts (like Rusty).

Internally they both call ondemand_readahead(), but the page argument is
changed to an obvious boolean flag.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00
Fengguang Wu
d8983910a4 readahead: pass real splice size
Pass real splice size to page_cache_readahead_ondemand().

The splice code works in chunks of 16 pages internally.  The readahead code
should be told of the overall splice size, instead of the internal chunk size.
 Otherwize bad things may happen.  Imagine some 17-page random splice reads.
The code before this patch will result in two readahead calls: readahead(16);
readahead(1); That leads to one 16-page I/O and one 32-page I/O: one extra I/O
and 31 readahead miss pages.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00
Fengguang Wu
431a4820bf readahead: move synchronous readahead call out of splice loop
Move synchronous page_cache_readahead_ondemand() call out of splice loop.

This avoids one pointless page allocation/insertion in case of non-zero
ra_pages, or many pointless readahead calls in case of zero ra_pages.

Note that if a user sets ra_pages to less than PIPE_BUFFERS=16 pages, he will
not get expected readahead behavior anyway.  The splice code works in batches
of 16 pages, which can be taken as another form of synchronous readahead.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00
Fengguang Wu
a08a166fe7 readahead: convert splice invocations
Convert splice reads to use on-demand readahead.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00
Jens Axboe
bcd4f3acba splice: direct splicing updates ppos twice
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> reported that he's noticed
nfsd read corruption in recent kernels, and did the hard work of
discovering that it's due to splice updating the file position twice.
This means that the next operation would start further ahead than it
should.

nfsd_vfs_read()
    splice_direct_to_actor()
        while(len) {
            do_splice_to()                     [update sd->pos]
                -> generic_file_splice_read()  [read from sd->pos]
            nfsd_direct_splice_actor()
                -> __splice_from_pipe()        [update sd->pos]

There's nothing wrong with the core splice code, but the direct
splicing is an addon that calls both input and output paths.
So it has to take care in locally caching offset so it remains correct.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-16 15:02:48 +02:00
Jens Axboe
51a92c0f6c splice: fix offset mangling with direct splicing (sendfile)
If the output actor doesn't transfer the full amount of data, we will
increment ppos too much. Two related bugs in there:

- We need to break out and return actor() retval if it is shorted than
  what we spliced into the pipe.

- Adjust ppos only according to actor() return.

Also fix loop problem in generic_file_splice_read(), it should not keep
going when data has already been transferred.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-13 14:14:31 +02:00
James Morris
29ce20586b security: revalidate rw permissions for sys_splice and sys_vmsplice
Revalidate read/write permissions for splice(2) and vmslice(2), in case
security policy has changed since the files were opened.

Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-13 14:14:29 +02:00
Jens Axboe
0845718daf pipe: add documentation and comments
As per Andrew Mortons request, here's a set of documentation for
the generic pipe_buf_operations hooks, the pipe, and pipe_buffer
structures.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:16 +02:00
Jens Axboe
cac36bb06e pipe: change the ->pin() operation to ->confirm()
The name 'pin' was badly chosen, it doesn't pin a pipe buffer
in the most commonly used sense in the kernel. So change the
name to 'confirm', after debating this issue with Hugh
Dickins a bit.

A good return from ->confirm() means that the buffer is really
there, and that the contents are good.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:15 +02:00
Jens Axboe
932cc6d4f7 splice: completely document external interface with kerneldoc
Also add fs/splice.c as a kerneldoc target with a smaller blurb that
should be expanded to better explain the overview of splice.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:15 +02:00
Jens Axboe
497f9625c2 pipe: allow passing around of ops private pointer
relay needs this for proper consumption handling, and the network
receive support needs it as well to lookup the sk_buff on pipe
release.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:14 +02:00
Jens Axboe
d6b29d7cee splice: divorce the splice structure/function definitions from the pipe header
We need to move even more stuff into the header so that folks can use
the splice_to_pipe() implementation instead of open-coding a lot of
pipe knowledge (see relay implementation), so move to our own header
file finally.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:14 +02:00
Jens Axboe
6a14b90bb6 vmsplice: add vmsplice-to-user support
A bit of a cheat, it actually just copies the data to userspace. But
this makes the interface nice and symmetric and enables people to build
on splice, with room for future improvement in performance.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:12 +02:00
Jens Axboe
c66ab6fa70 splice: abstract out actor data
For direct splicing (or private splicing), the output may not be a file.
So abstract out the handling into a specified actor function and put
the data in the splice_desc structure earlier, so we can build on top
of that.

This is the first step in better splice handling for drivers, and also
for implementing vmsplice _to_ user memory.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-10 08:04:12 +02:00
Jens Axboe
02676e5aee splice: only check do_wakeup in splice_to_pipe() for a real pipe
We only ever set do_wakeup to non-zero if the pipe has an inode
backing, so it's pointless to check outside the pipe->inode
check.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-15 13:16:13 +02:00
Jens Axboe
00de00bdad splice: fix leak of pages on short splice to pipe
If the destination pipe is full and we already transferred
data, we break out instead of waiting for more pipe room.
The exit logic looks at spd->nr_pages to see if we moved
everything inside the spd container, but we decrement that
variable in the loop to decide when spd has emptied.

Instead we want to compare to the original page count in
the spd, so cache that in a local variable.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-15 13:14:22 +02:00
Jens Axboe
17ee4f49ab splice: adjust balance_dirty_pages_ratelimited() call
As we have potentially dirtied more than 1 page, we should indicate as
such to the dirty page balancing. So call
balance_dirty_pages_ratelimited_nr() and pass in the approximate number
of pages we dirtied.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-15 13:10:37 +02:00
Jens Axboe
620a324b74 splice: __generic_file_splice_read: fix read/truncate race
Original patch and description from Neil Brown <neilb@suse.de>,
merged and adapted to splice branch by me. Neils text follows:

__generic_file_splice_read() currently samples the i_size at the start
and doesn't do so again unless it needs to call ->readpage to load
a page.  After ->readpage it has to re-sample i_size as a truncate
may have caused that page to be filled with zeros, and the read()
call should not see these.

However there are other activities that might cause ->readpage to be
called on a page between the time that __generic_file_splice_read()
samples i_size and when it finds that it has an uptodate page. These
include at least read-ahead and possibly another thread performing a
read

So we must sample i_size *after* it has an uptodate page.  Thus the
current sampling at the start and after a read can be replaced with a
sampling before page addition into spd.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-08 08:34:11 +02:00
Hugh Dickins
475ecade68 splice: __generic_file_splice_read: fix i_size_read() length checks
__generic_file_splice_read's partial page check, at eof after readpage,
not only got its calculations wrong, but also reused the loff variable:
causing data corruption when splicing from a non-0 offset in the file's
last page (revealed by ext2 -b 1024 testing on a loop of a tmpfs file).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-08 08:34:05 +02:00
Jens Axboe
20d698db67 splice: move balance_dirty_pages_ratelimited() outside of splice actor
I've seen inode related deadlocks, so move this call outside of the
actor itself, which may hold the inode lock.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-08 08:33:59 +02:00
Jens Axboe
267adc3e66 splice: remove do_splice_direct() symbol export
It's only supposed to be used by do_sendfile(), which is never
modular. So kill the export.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-08 08:33:41 +02:00
Jens Axboe
d366d39885 splice: move inode size check into generic_file_splice_read()
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-06-08 08:32:38 +02:00
Jens Axboe
86aa5ac53e [PATCH] splice: always call into page_cache_readahead()
Don't try to guess what the read-ahead logic will do, allow it
to make its own decisions.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-05-08 08:46:19 +02:00
Fengguang Wu
9ae9d68cbf [PATCH] splice(): fix interaction with readahead
Eric Dumazet, thank you for disclosing this bug.

Readahead logic somehow fails to populate the page range with data.
It can be because

1) the readahead routine is not always called in the following lines of

fs/splice.c:
        if (!loff || nr_pages > 1)
                page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);

2) even called, page_cache_readahead() wont guarantee the pages are there.
It wont submit readahead I/O for pages already in the radix tree, or when
(ra_pages == 0), or after 256 cache hits.

In your case, it should be because of the retried reads, which lead to
excessive cache hits, and disables readahead at some time.

And that _one_ failure of readahead blocks the whole read process.
The application receives EAGAIN and retries the read, but
__generic_file_splice_read() refuse to make progress:

- in the previous invocation, it has allocated a blank page and inserted it
  into the radix tree, but never has the chance to start I/O for it: the test
  of SPLICE_F_NONBLOCK goes before that.

- in the retried invocation, the readahead code will neither get out of the
  cache hit mode, nor will it submit I/O for an already existing page.

Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-05-08 08:44:36 +02:00
Dmitriy Monakhov
d9993c37ef [PATCH] splice: partial write fix
Currently if partial write has happened while ->commit_write() then page
wasn't marked as accessed and rebalanced.

Signed-off-by: Monakhov Dmitriy <dmonakhov@openvz.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-03-29 14:26:42 +02:00
Mark Fasheh
40bee44eae Export __splice_from_pipe()
Ocfs2 wants to implement it's own splice write actor so that it can better
manage cluster / page locks. This lets us re-use the rest of splice write
while only providing our own code where it's actually important.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-03-27 08:55:47 +02:00
Nick Piggin
08c7259163 2/2 splice: dont readpage
Splice does not need to readpage to bring the page uptodate before writing
to it, because prepare_write will take care of that for us.

Splice is also wrong to SetPageUptodate before the page is actually uptodate.
This results in the old uninitialised memory leak. This gets fixed as a
matter of course when removing the readpage logic.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-03-27 08:55:39 +02:00
Nick Piggin
485ddb4b97 1/2 splice: dont steal
Stealing pages with splice is problematic because we cannot just insert
an uptodate page into the pagecache and hope the filesystem can take care
of it later.

We also cannot just ClearPageUptodate, then hope prepare_write does not
write anything into the page, because I don't think prepare_write gives
that guarantee.

Remove support for SPLICE_F_MOVE for now. If we really want to bring it
back, we might be able to do so with a the new filesystem buffered write
aops APIs I'm working on. If we really don't want to bring it back, then
we should decide that sooner rather than later, and remove the flag and
all the stealing infrastructure before anybody starts using it.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-03-27 08:55:08 +02:00
Eric Dumazet
d4c3cca941 [PATCH] constify pipe_buf_operations
- pipe/splice should use const pipe_buf_operations and file_operations

- struct pipe_inode_info has an unused field "start" : get rid of it.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 09:05:47 -08:00
Josef "Jeff" Sipek
0f7fc9e4d0 [PATCH] VFS: change struct file to use struct path
This patch changes struct file to use struct path instead of having
independent pointers to struct dentry and struct vfsmount, and converts all
users of f_{dentry,vfsmnt} in fs/ to use f_path.{dentry,mnt}.

Additionally, it adds two #define's to make the transition easier for users of
the f_dentry and f_vfsmnt.

Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08 08:28:41 -08:00
Jens Axboe
ddac0d39cf [PATCH] splice: fix problem introduced with inode diet
After the inode slimming patch that unionised i_pipe/i_bdev/i_cdev, it's
no longer enough to check for existance of ->i_pipe to verify that this
is a pipe.

Original patch from Eric Dumazet <dada1@cosmosbay.com>
Final solution suggested by Linus.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-04 08:45:39 -08:00
Nick Piggin
2ae88149a2 [PATCH] mm: clean up pagecache allocation
- Consolidate page_cache_alloc

- Fix splice: only the pagecache pages and filesystem data need to use
  mapping_gfp_mask.

- Fix grab_cache_page_nowait: same as splice, also honour NUMA placement.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-28 11:30:50 -07:00
Jens Axboe
8c34e2d632 [PATCH] Remove SUID when splicing into an inode
Originally from Mark Fasheh <mark.fasheh@oracle.com>

generic_file_splice_write() does not remove S_ISUID or S_ISGID. This is
inconsistent with the way we generally write to files.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-10-19 20:53:09 +02:00
Mark Fasheh
6da6180982 [PATCH] Introduce generic_file_splice_write_nolock()
This allows file systems to manage their own i_mutex locking while
still re-using the generic_file_splice_write() logic.

OCFS2 in particular wants this so that it can order cluster locks within
i_mutex.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-10-19 20:53:08 +02:00
Mark Fasheh
62752ee198 [PATCH] Take i_mutex in splice_from_pipe()
The splice_actor may be calling ->prepare_write() and ->commit_write(). We
want i_mutex on the inode being written to before calling those so that we
don't race i_size changes.

The double locking behavior is done elsewhere in splice.c, and if we
eventually want _nolock variants of generic_file_splice_write(), fs modules
might have to replicate the nasty locking code. We introduce
inode_double_lock() and inode_double_unlock() to consolidate the locking
rules into one set of functions.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-10-19 20:53:08 +02:00
Jens Axboe
e6e80f294c [PATCH] splice: fix pipe_to_file() ->prepare_write() error path
Don't jump to the unlock+release path, we already did that.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-10-12 15:08:51 +02:00
Jens Axboe
0fe2347957 [PATCH] Update axboe@suse.de email address
As people often look for the copyright in files to see who to mail,
update the link to a neutral one.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 20:52:34 +02:00
Jens Axboe
aadd06e5c5 [PATCH] splice: fix problems with sys_tee()
Several issues noticed/fixed:

- We cannot reliably block in link_pipe() while holding both input and output
  mutexes. So do preparatory checks before locking down both mutexes and doing
  the link.

- The ipipe->nrbufs vs i check was bad, because we could have dropped the
  ipipe lock in-between. This causes us to potentially look at unknown
  buffers if we were racing with someone else reading this pipe.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-07-10 11:00:01 +02:00
Jens Axboe
9e94cd4fd1 [PATCH] splice: retrieve mapping after locking the page
Otherwise we could be racing with truncate/mapping removal.

Problem found/fixed by Nick Piggin <npiggin@suse.de>, logic rewritten
by me.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-06-23 17:10:39 +02:00
Jens Axboe
a0548871ed [PATCH] splice: redo page lookup if add_to_page_cache() returns -EEXIST
This can happen quite easily, if several processes are trying to splice
the same file at the same time. It's not a failure, it just means someone
raced with us in allocating this file page. So just dump the allocated
page and relookup the original.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-04 06:55:12 +02:00
Jens Axboe
76ad4d1110 [PATCH] splice: rename remaining info variables to pipe
Same thing was done in fs/pipe.c and most of fs/splice.c, but we had
a few missing still.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-04 06:55:12 +02:00
Jens Axboe
1432873af7 [PATCH] splice: LRU fixups
Nick says that the current construct isn't safe. This goes back to the
original, but sets PIPE_BUF_FLAG_LRU on user pages as well as they all
seem to be on the LRU in the first place.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-04 06:55:12 +02:00
Jens Axboe
bfc4ee39fd [PATCH] splice: fix unlocking of page on error ->prepare_write()
Looking at generic_file_buffered_write(), we need to unlock_page() if
prepare write fails and it isn't due to racing with truncate().

Also trim the size if ->prepare_write() fails, if we have to.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-04 06:55:12 +02:00
Jens Axboe
330ab71619 [PATCH] vmsplice: restrict stealing a little more
Apply the same rules as the anon pipe pages, only allow stealing
if no one else is using the page.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-02 15:29:57 +02:00
Jens Axboe
a893b99be7 [PATCH] splice: fix page LRU accounting
Currently we rely on the PIPE_BUF_FLAG_LRU flag being set correctly
to know whether we need to fiddle with page LRU state after stealing it,
however for some origins we just don't know if the page is on the LRU
list or not.

So remove PIPE_BUF_FLAG_LRU and do this check/add manually in pipe_to_file()
instead.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-02 15:03:27 +02:00
Jens Axboe
7591489a8f [PATCH] vmsplice: fix badly placed end paranthesis
We need to use the minium of {len, PAGE_SIZE-off}, not {len, PAGE_SIZE}-off.
The latter doesn't make any sense, and could cause us to attempt negative
length transfers...

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-02 12:57:18 +02:00
Jens Axboe
7afa6fd037 [PATCH] vmsplice: allow user to pass in gift pages
If SPLICE_F_GIFT is set, the user is basically giving this pages away to
the kernel. That means we can steal them for eg page cache uses instead
of copying it.

The data must be properly page aligned and also a multiple of the page size
in length.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-05-01 20:02:33 +02:00