linux-stable.git/fs/btrfs/compression.c, branch linux-3.12.y

mm + fs: prepare for non-page entries in page cache radix trees

2014-09-26T09:51:58+00:00

commit 0cd6144aadd2afd19d1aca880153530c52957604 upstream.

shmem mappings already contain exceptional entries where swap slot
information is remembered.

To be able to store eviction information for regular page cache, prepare
every site dealing with the radix trees directly to handle entries other
than pages.

The common lookup functions will filter out non-page entries and return
NULL for page cache holes, just as before.  But provide a raw version of
the API which returns non-page entries as well, and switch shmem over to
use it.

Signed-off-by: Johannes Weiner 
Reviewed-by: Rik van Riel 
Reviewed-by: Minchan Kim 
Cc: Andrea Arcangeli 
Cc: Bob Liu 
Cc: Christoph Hellwig 
Cc: Dave Chinner 
Cc: Greg Thelen 
Cc: Hugh Dickins 
Cc: Jan Kara 
Cc: KOSAKI Motohiro 
Cc: Luigi Semenzato 
Cc: Mel Gorman 
Cc: Metin Doslu 
Cc: Michel Lespinasse 
Cc: Ozgun Erdogan 
Cc: Peter Zijlstra 
Cc: Roman Gushchin 
Cc: Ryan Mallon 
Cc: Tejun Heo 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Mel Gorman 
Signed-off-by: Jiri Slaby

Btrfs: fix data corruption when reading/updating compressed extents

2014-03-01T19:44:41+00:00

commit a2aa75e18a21b21952dc6daa9bac7c9f4426f81f upstream.

When using a mix of compressed file extents and prealloc extents, it
is possible to fill a page of a file with random, garbage data from
some unrelated previous use of the page, instead of a sequence of zeroes.

A simple sequence of steps to get into such case, taken from the test
case I made for xfstests, is:

   _scratch_mkfs
   _scratch_mount "-o compress-force=lzo"
   $XFS_IO_PROG -f -c "pwrite -S 0x06 -b 18670 266978 18670" $SCRATCH_MNT/foobar
   $XFS_IO_PROG -c "falloc 26450 665194" $SCRATCH_MNT/foobar
   $XFS_IO_PROG -c "truncate 542872" $SCRATCH_MNT/foobar
   $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar

This results in the following file items in the fs tree:

   item 4 key (257 INODE_ITEM 0) itemoff 15879 itemsize 160
       inode generation 6 transid 6 size 542872 block group 0 mode 100600
   item 5 key (257 INODE_REF 256) itemoff 15863 itemsize 16
       inode ref index 2 namelen 6 name: foobar
   item 6 key (257 EXTENT_DATA 0) itemoff 15810 itemsize 53
       extent data disk byte 0 nr 0 gen 6
       extent data offset 0 nr 24576 ram 266240
       extent compression 0
   item 7 key (257 EXTENT_DATA 24576) itemoff 15757 itemsize 53
       prealloc data disk byte 12849152 nr 241664 gen 6
       prealloc data offset 0 nr 241664
   item 8 key (257 EXTENT_DATA 266240) itemoff 15704 itemsize 53
       extent data disk byte 12845056 nr 4096 gen 6
       extent data offset 0 nr 20480 ram 20480
       extent compression 2
   item 9 key (257 EXTENT_DATA 286720) itemoff 15651 itemsize 53
       prealloc data disk byte 13090816 nr 405504 gen 6
       prealloc data offset 0 nr 258048

The on disk extent at offset 266240 (which corresponds to 1 single disk block),
contains 5 compressed chunks of file data. Each of the first 4 compress 4096
bytes of file data, while the last one only compresses 3024 bytes of file data.
Therefore a read into the file region [285648 ; 286720[ (length = 4096 - 3024 =
1072 bytes) should always return zeroes (our next extent is a prealloc one).

The solution here is the compression code path to zero the remaining (untouched)
bytes of the last page it uncompressed data into, as the information about how
much space the file data consumes in the last page is not known in the upper layer
fs/btrfs/extent_io.c:__do_readpage(). In __do_readpage we were correctly zeroing
the remainder of the page but only if it corresponds to the last page of the inode
and if the inode's size is not a multiple of the page size.

This would cause not only returning random data on reads, but also permanently
storing random data when updating parts of the region that should be zeroed.
For the example above, it means updating a single byte in the region [285648 ; 286720[
would store that byte correctly but also store random data on disk.

A test case for xfstests follows soon.

Signed-off-by: Filipe David Borba Manana 
Signed-off-by: Chris Mason 
Signed-off-by: Jiri Slaby

Btrfs: Remove superfluous casts from u64 to unsigned long long

2013-09-01T12:16:08+00:00

u64 is "unsigned long long" on all architectures now, so there's no need to
cast it when formatting it using the "ll" length modifier.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

btrfs: Introduce extent_read_full_page_nolock()

2013-09-01T12:04:59+00:00

We want this for btrfs_extent_same. Basically readpage and friends do their
own extent locking but for the purposes of dedupe, we want to have both
files locked down across a set of readpage operations (so that we can
compare data). Introduce this variant and a flag which can be set for
extent_read_full_page() to indicate that we are already locked.

Partial credit for this patch goes to Gabriel de Perthuis 
as I have included a fix from him to the original patch which avoids a
deadlock on compressed extents.

Signed-off-by: Mark Fasheh 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

btrfs: make static code static & remove dead code

2013-05-06T19:55:23+00:00

Big patch, but all it does is add statics to functions which
are in fact static, then remove the associated dead-code fallout.

removed functions:

btrfs_iref_to_path()
__btrfs_lookup_delayed_deletion_item()
__btrfs_search_delayed_insertion_item()
__btrfs_search_delayed_deletion_item()
find_eb_for_page()
btrfs_find_block_group()
range_straddles_pages()
extent_range_uptodate()
btrfs_file_extent_length()
btrfs_scrub_cancel_devid()
btrfs_start_transaction_lflush()

btrfs_print_tree() is left because it is used for debugging.
btrfs_start_transaction_lflush() and btrfs_reada_detach() are
left for symmetry.

ulist.c functions are left, another patch will take care of those.

Signed-off-by: Eric Sandeen 
Signed-off-by: Josef Bacik

Btrfs: cleanup unused arguments of btrfs_csum_data

2013-05-06T19:54:14+00:00

Argument 'root' is no more used in btrfs_csum_data().

Signed-off-by: Liu Bo 
Signed-off-by: Josef Bacik

Btrfs: add rw argument to merge_bio_hook()

2013-02-01T16:49:47+00:00

We'll want to merge writes so they can fill a full RAID[56] stripe, but
not necessarily reads.

Signed-off-by: David Woodhouse 
Signed-off-by: Chris Mason

Btrfs: handle errors from btrfs_map_bio() everywhere

2012-12-12T22:15:40+00:00

With the addition of the device replace procedure, it is possible
for btrfs_map_bio(READ) to report an error. This happens when the
specific mirror is requested which is located on the target disk,
and the copy operation has not yet copied this block. Hence the
block cannot be read and this error state is indicated by
returning EIO.
Some background information follows now. A new mirror is added
while the device replace procedure is running.
btrfs_get_num_copies() returns one more, and
btrfs_map_bio(GET_READ_MIRROR) adds one more mirror if a disk
location is involved that was already handled by the device
replace copy operation. The assigned mirror num is the highest
mirror number, e.g. the value 3 in case of RAID1.
If btrfs_map_bio() is invoked with mirror_num == 0 (i.e., select
any mirror), the copy on the target drive is never selected
because that disk shall be able to perform the write requests as
quickly as possible. The parallel execution of read requests would
only slow down the disk copy procedure. Second case is that
btrfs_map_bio() is called with mirror_num > 0. This is done from
the repair code only. In this case, the highest mirror num is
assigned to the target disk, since it is used last. And when this
mirror is not available because the copy procedure has not yet
handled this area, an error is returned. Everywhere in the code
the handling of such errors is added now.

Signed-off-by: Stefan Behrens 
Signed-off-by: Chris Mason

Btrfs: cleanup pages properly when ENOMEM in compression

2012-10-09T13:20:25+00:00

We were freeing non-existent pages which was causing a panic for a user who
was suffering from ENOMEM.  This patch fixes the problem.  Thanks,

Reported-by: Jérôme Poulin 
Signed-off-by: Josef Bacik

Btrfs: barrier before waitqueue_active

2012-08-28T20:53:33+00:00

We need a barrir before calling waitqueue_active otherwise we will miss
wakeups.  So in places that do atomic_dec(); then atomic_read() use
atomic_dec_return() which imply a memory barrier (see memory-barriers.txt)
and then add an explicit memory barrier everywhere else that need them.
Thanks,

Signed-off-by: Josef Bacik