linux.git/fs/splice.c, branch v2.6.30

splice: fix new kernel-doc warnings

2009-04-17T14:38:07+00:00

splice: fix kernel-doc warnings

  Warning(fs/splice.c:617): bad line:
  Warning(fs/splice.c:722): No description found for parameter 'sd'
  Warning(fs/splice.c:722): Excess function parameter 'pipe' description in 'splice_from_pipe_begin'

Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

splice: add helpers for locking pipe inode

2009-04-15T10:10:12+00:00

There are lots of sequences like this, especially in splice code:

	if (pipe->inode)
		mutex_lock(&pipe->inode->i_mutex);
	/* do something */
	if (pipe->inode)
		mutex_unlock(&pipe->inode->i_mutex);

so introduce helpers which do the conditional locking and unlocking.
Also replace the inode_double_lock() call with a pipe_double_lock()
helper to avoid spreading the use of this functionality beyond the
pipe code.

This patch is just a cleanup, and should cause no behavioral changes.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

splice: remove generic_file_splice_write_nolock()

2009-04-15T10:10:12+00:00

Remove the now unused generic_file_splice_write_nolock() function.
It's conceptually broken anyway, because splice may need to wait for
pipe events so holding locks across the whole operation is wrong.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

ocfs2: fix i_mutex locking in ocfs2_splice_to_file()

2009-04-15T10:10:12+00:00

Rearrange locking of i_mutex on destination and call to
ocfs2_rw_lock() so locks are only held while buffers are copied with
the pipe_to_file() actor, and not while waiting for more data on the
pipe.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

splice: fix i_mutex locking in generic_splice_write()

2009-04-15T10:10:11+00:00

Rearrange locking of i_mutex on destination so it's only held while
buffers are copied with the pipe_to_file() actor, and not while
waiting for more data on the pipe.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

splice: remove i_mutex locking in splice_from_pipe()

2009-04-15T10:10:11+00:00

splice_from_pipe() is only called from two places:

  - generic_splice_sendpage()
  - splice_write_null()

Neither of these require i_mutex to be taken on the destination inode.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

splice: split up __splice_from_pipe()

2009-04-15T10:10:11+00:00

Split up __splice_from_pipe() into four helper functions:

  splice_from_pipe_begin()
  splice_from_pipe_next()
  splice_from_pipe_feed()
  splice_from_pipe_end()

splice_from_pipe_next() will wait (if necessary) for more buffers to
be added to the pipe.  splice_from_pipe_feed() will feed the buffers
to the supplied actor and return when there's no more data available
(or if all of the requested data has been copied).

This is necessary so that implementations can do locking around the
non-waiting splice_from_pipe_feed().

This patch should not cause any change in behavior.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

splice: fix deadlock in splicing to file

2009-04-07T15:34:46+00:00

There's a possible deadlock in generic_file_splice_write(),
splice_from_pipe() and ocfs2_file_splice_write():

 - task A calls generic_file_splice_write()
 - this calls inode_double_lock(), which locks i_mutex on both
   pipe->inode and target inode
 - ordering depends on inode pointers, can happen that pipe->inode is
   locked first
 - __splice_from_pipe() needs more data, calls pipe_wait()
 - this releases lock on pipe->inode, goes to interruptible sleep
 - task B calls generic_file_splice_write(), similarly to the first
 - this locks pipe->inode, then tries to lock inode, but that is
   already held by task A
 - task A is interrupted, it tries to lock pipe->inode, but fails, as
   it is already held by task B
 - ABBA deadlock

Fix this by explicitly ordering locks: the outer lock must be on
target inode and the inner lock (which is later unlocked and relocked)
must be on pipe->inode.  This is OK, pipe inodes and target inodes
form two nonoverlapping sets, generic_file_splice_write() and friends
are not called with a target which is a pipe.

Signed-off-by: Miklos Szeredi 
Acked-by: Mark Fasheh 
Acked-by: Jens Axboe 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

FS-Cache: Recruit a page flags for cache management

2009-04-03T15:42:36+00:00

Recruit a page flag to aid in cache management.  The following extra flag is
defined:

 (1) PG_fscache (PG_private_2)

     The marked page is backed by a local cache and is pinning resources in the
     cache driver.

If PG_fscache is set, then things that checked for PG_private will now also
check for that.  This includes things like truncation and page invalidation.
The function page_has_private() had been added to make the checks for both
PG_private and PG_private_2 at the same time.

Signed-off-by: David Howells 
Acked-by: Steve Dickson 
Acked-by: Trond Myklebust 
Acked-by: Rik van Riel 
Acked-by: Al Viro 
Tested-by: Daire Byrne

[CVE-2009-0029] System call wrappers part 31

2009-01-14T13:15:31+00:00

Signed-off-by: Heiko Carstens