linux-toradex.git/fs/btrfs/extent_map.c, branch v4.5

btrfs: cleanup, stop casting for extent_map->lookup everywhere

2016-01-15T18:22:28+00:00

Overloading extent_map->bdev to struct map_lookup * might have started out
as a means to an end, but it's a pattern that's used all over the place
now. Let's get rid of the casting and just add a union instead.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba

Btrfs: do not move em to modified list when unpinning

2014-11-21T19:59:54+00:00

We use the modified list to keep track of which extents have been modified so we
know which ones are candidates for logging at fsync() time.  Newly modified
extents are added to the list at modification time, around the same time the
ordered extent is created.  We do this so that we don't have to wait for ordered
extents to complete before we know what we need to log.  The problem is when
something like this happens

log extent 0-4k on inode 1
copy csum for 0-4k from ordered extent into log
sync log
commit transaction
log some other extent on inode 1
ordered extent for 0-4k completes and adds itself onto modified list again
log changed extents
see ordered extent for 0-4k has already been logged
	at this point we assume the csum has been copied
sync log
crash

On replay we will see the extent 0-4k in the log, drop the original 0-4k extent
which is the same one that we are replaying which also drops the csum, and then
we won't find the csum in the log for that bytenr.  This of course causes us to
have errors about not having csums for certain ranges of our inode.  So remove
the modified list manipulation in unpin_extent_cache, any modified extents
should have been added well before now, and we don't want them re-logged.  This
fixes my test that I could reliably reproduce this problem with.  Thanks,

cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: fix NULL pointer crash when running balance and scrub concurrently

2014-06-19T21:20:55+00:00

While running balance, scrub, fsstress concurrently we hit the
following kernel crash:

[56561.448845] BTRFS info (device sde): relocating block group 11005853696 flags 132
[56561.524077] BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
[56561.524237] IP: [] scrub_chunk.isra.12+0xdd/0x130 [btrfs]
[56561.524297] PGD 9be28067 PUD 7f3dd067 PMD 0
[56561.524325] Oops: 0000 [#1] SMP
[....]
[56561.527237] Call Trace:
[56561.527309]  [] scrub_enumerate_chunks+0x24e/0x490 [btrfs]
[56561.527392]  [] ? abort_exclusive_wait+0x50/0xb0
[56561.527476]  [] btrfs_scrub_dev+0x1a4/0x530 [btrfs]
[56561.527561]  [] btrfs_ioctl+0x13f7/0x2a90 [btrfs]
[56561.527639]  [] do_vfs_ioctl+0x2e0/0x4c0
[56561.527712]  [] ? vtime_account_user+0x54/0x60
[56561.527788]  [] ? __audit_syscall_entry+0x9c/0xf0
[56561.527870]  [] SyS_ioctl+0x81/0xa0
[56561.527941]  [] tracesys+0xdd/0xe2
[...]
[56561.528304] RIP  [] scrub_chunk.isra.12+0xdd/0x130 [btrfs]
[56561.528395]  RSP 
[56561.528454] CR2: 0000000000000078

This is because in btrfs_relocate_chunk(), we will free @bdev directly while
scrub may still hold extent mapping, and may access freed memory.

Fix this problem by wrapping freeing @bdev work into free_extent_map() which
is based on reference count.

Reported-by: Qu Wenruo 
Signed-off-by: Wang Shilong 
Signed-off-by: Miao Xie 
Signed-off-by: Chris Mason

Btrfs: more efficient btrfs_drop_extent_cache

2014-03-10T19:16:57+00:00

While droping extent map structures from the extent cache that cover our
target range, we would remove each extent map structure from the red black
tree and then add either 1 or 2 new extent map structures if the former
extent map covered sections outside our target range.

This change simply attempts to replace the existing extent map structure
with a new one that covers the subsection we're not interested in, instead
of doing a red black remove operation followed by an insertion operation.

The number of elements in an inode's extent map tree can get very high for large
files under random writes. For example, while running the following test:

    sysbench --test=fileio --file-num=1 --file-total-size=10G \
        --file-test-mode=rndrw --num-threads=32 --file-block-size=32768 \
        --max-requests=500000 --file-rw-ratio=2 [prepare|run]

I captured the following histogram capturing the number of extent_map items
in the red black tree while that test was running:

    Count: 122462
    Range:  1.000 - 172231.000; Mean: 96415.831; Median: 101855.000; Stddev: 49700.981
    Percentiles:  90th: 160120.000; 95th: 166335.000; 99th: 171070.000
       1.000 -    5.231:   452 |
       5.231 -  187.392:    87 |
     187.392 -  585.911:   206 |
     585.911 - 1827.438:   623 |
    1827.438 - 5695.245:  1962 #
    5695.245 - 17744.861:  6204 ####
   17744.861 - 55283.764: 21115 ############
   55283.764 - 172231.000: 91813 #####################################################

Benchmark:

    sysbench --test=fileio --file-num=1 --file-total-size=10G --file-test-mode=rndwr \
        --num-threads=64 --file-block-size=32768 --max-requests=0 --max-time=60 \
        --file-io-mode=sync --file-fsync-freq=0 [prepare|run]

Before this change: 122.1Mb/sec
After this change:  125.07Mb/sec
(averages of 5 test runs)

Test machine: quad core intel i5-3570K, 32Gb of ram, SSD

Signed-off-by: Filipe David Borba Manana 
Signed-off-by: Josef Bacik

Btrfs: remove unneeded field / smaller extent_map structure

2014-03-10T19:16:56+00:00

We don't need to have an unsigned int field in the extent_map struct
to tell us whether the extent map is in the inode's extent_map tree or
not. We can use the rb_node struct field and the RB_CLEAR_NODE and
RB_EMPTY_NODE macros to achieve the same task.

This reduces sizeof(struct extent_map) from 152 bytes to 144 bytes (on a
64 bits system).

Signed-off-by: Filipe David Borba Manana 
Reviewed-by: David Sterba 
Signed-off-by: Josef Bacik

Btrfs: fix extent_map block_len after merging

2014-01-28T21:19:51+00:00

When merging an extent_map with its right neighbor, increment
its block_len with the neighbor's block_len.

Signed-off-by: Filipe David Borba Manana 
Signed-off-by: Josef Bacik 
Signed-off-by: Chris Mason

Btrfs: faster and more efficient extent map insertion

2014-01-28T21:19:48+00:00

Before this change, adding an extent map to the extent map tree of an
inode required 2 tree nevigations:

1) doing a tree navigation to search for an existing extent map starting
   at the same offset or an extent map that overlaps the extent map we
   want to insert;

2) Another tree navigation to add the extent map to the tree (if the
   former tree search didn't found anything).

This change just merges these 2 steps into a single one.
While running first few btrfs xfstests I had noticed these trees easily
had a few hundred elements, and then with the following sysbench test it
reached over 1100 elements very often.

Test:

  sysbench --test=fileio --file-num=32 --file-total-size=10G \
    --file-test-mode=seqwr --num-threads=512 --file-block-size=8192 \
    --max-requests=1000000 --file-io-mode=sync [prepare|run]

(fs created with mkfs.btrfs -l 4096 -f /dev/sdb3 before each sysbench
prepare phase)

Before this patch:

run 1 - 41.894Mb/sec
run 2 - 40.527Mb/sec
run 3 - 40.922Mb/sec
run 4 - 49.433Mb/sec
run 5 - 40.959Mb/sec

average - 42.75Mb/sec

After this patch:

run 1 - 48.036Mb/sec
run 2 - 50.21Mb/sec
run 3 - 50.929Mb/sec
run 4 - 46.881Mb/sec
run 5 - 53.192Mb/sec

average - 49.85Mb/sec

Signed-off-by: Filipe David Borba Manana 
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: fix bad extent logging

2013-05-06T19:54:34+00:00

A user sent me a btrfs-image of a file system that was panicing on mount during
the log recovery.  I had originally thought these problems were from a bug in
the free space cache code, but that was just a symptom of the problem.  The
problem is if your application does something like this

[prealloc][prealloc][prealloc]

the internal extent maps will merge those all together into one extent map, even
though on disk they are 3 separate extents.  So if you go to write into one of
these ranges the extent map will be right since we use the physical extent when
doing the write, but when we log the extents they will use the wrong sizes for
the remainder prealloc space.  If this doesn't happen to trip up the free space
cache (which it won't in a lot of cases) then you will get bogus entries in your
extent tree which will screw stuff up later.  The data and such will still work,
but everything else is broken.  This patch fixes this by not allowing extents
that are on the modified list to be merged.  This has the side effect that we
are no longer adding everything to the modified list all the time, which means
we now have to call btrfs_drop_extents every time we log an extent into the
tree.  So this allows me to drop all this speciality code I was using to get
around calling btrfs_drop_extents.  With this patch the testcase I've created no
longer creates a bogus file system after replaying the log.  Thanks,

Signed-off-by: Josef Bacik

btrfs: fixup/remove module.h usage as required

2013-03-01T20:01:01+00:00

We want to avoid module.h where posible, since it in turn includes
nearly all of header space.  This means removing it where it is not
required, and using export.h where we are only exporting symbols via
EXPORT_SYMBOL and friends.

Signed-off-by: Paul Gortmaker 
Signed-off-by: Chris Mason