linux-toradex.git/fs/btrfs/extent_map.c, branch v6.7

btrfs: fix incorrect splitting in btrfs_drop_extent_map_range

2023-08-18T12:38:10+00:00

In production we were seeing a variety of WARN_ON()'s in the extent_map
code, specifically in btrfs_drop_extent_map_range() when we have to call
add_extent_mapping() for our second split.

Consider the following extent map layout

	PINNED
	[0 16K)  [32K, 48K)

and then we call btrfs_drop_extent_map_range for [0, 36K), with
skip_pinned == true.  The initial loop will have

	start = 0
	end = 36K
	len = 36K

we will find the [0, 16k) extent, but since we are pinned we will skip
it, which has this code

	start = em_end;
	if (end != (u64)-1)
		len = start + len - em_end;

em_end here is 16K, so now the values are

	start = 16K
	len = 16K + 36K - 16K = 36K

len should instead be 20K.  This is a problem when we find the next
extent at [32K, 48K), we need to split this extent to leave [36K, 48k),
however the code for the split looks like this

	split->start = start + len;
	split->len = em_end - (start + len);

In this case we have

	em_end = 48K
	split->start = 16K + 36K       // this should be 16K + 20K
	split->len = 48K - (16K + 36K) // this overflows as 16K + 36K is 52K

and now we have an invalid extent_map in the tree that potentially
overlaps other entries in the extent map.  Even in the non-overlapping
case we will have split->start set improperly, which will cause problems
with any block related calculations.

We don't actually need len in this loop, we can simply use end as our
end point, and only adjust start up when we find a pinned extent we need
to skip.

Adjust the logic to do this, which keeps us from inserting an invalid
extent map.

We only skip_pinned in the relocation case, so this is relatively rare,
except in the case where you are running relocation a lot, which can
happen with auto relocation on.

Fixes: 55ef68990029 ("Btrfs: Fix btrfs_drop_extent_cache for skip pinned case")
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana 
Signed-off-by: Josef Bacik 
Signed-off-by: David Sterba

btrfs: pass the new logical address to split_extent_map

2023-06-19T11:59:33+00:00

split_extent_map splits off the first chunk of an extent map into a new
one.  One of the two users is the zoned I/O completion code that wants to
rewrite the logical block start address right after this split.  Pass in
the logical address to be set in the split off first extent_map as an
argument to avoid an extra extent tree lookup for this case.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Christoph Hellwig 
Signed-off-by: David Sterba

btrfs: move split_extent_map to extent_map.c

2023-06-19T11:59:33+00:00

split_extent_map doesn't have anything to do with the other code in
inode.c, so move it to extent_map.c.

This also allows marking replace_extent_mapping static.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: Christoph Hellwig 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: drop gfp from parameter extent state helpers

2023-06-19T11:59:30+00:00

Now that all extent state bit helpers effectively take the GFP_NOFS mask
(and GFP_NOWAIT is encoded in the bits) we can remove the parameter.
This reduces stack consumption in many functions and simplifies a lot of
code.

Net effect on module on a release build:

   text    data     bss     dec     hex filename
1250432   20985   16088 1287505  13a551 pre/btrfs.ko
1247074   20985   16088 1284147  139833 post/btrfs.ko

DELTA: -3358

Signed-off-by: David Sterba

btrfs: pass NOWAIT for set/clear extent bits as another bit

2023-06-19T11:59:30+00:00

The only flags we now pass to set_extent_bit/__clear_extent_bit are
GFP_NOFS and GFP_NOWAIT (a few functions handling mappings). This
requires an extra parameter to be passed everywhere but is almost always
the same.

Encode the GFP_NOWAIT as an artificial extent bit and extract the
real bits and gfp mask in the lowest level helpers. Now the passed
gfp mask is not actually used and can be removed.

Signed-off-by: David Sterba

btrfs: open code set_extent_bits_nowait

2023-06-19T11:59:30+00:00

The helper only passes GFP_NOWAIT as gfp flags and is used two times.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: fix extent map logging bit not cleared for split maps after dropping range

2023-03-06T18:28:19+00:00

At btrfs_drop_extent_map_range() we are clearing the EXTENT_FLAG_LOGGING
bit on a 'flags' variable that was not initialized. This makes static
checkers complain about it, so initialize the 'flags' variable before
clearing the bit.

In practice this has no consequences, because EXTENT_FLAG_LOGGING should
not be set when btrfs_drop_extent_map_range() is called, as an fsync locks
the inode in exclusive mode, locks the inode's mmap semaphore in exclusive
mode too and it always flushes all delalloc.

Also add a comment about why we clear EXTENT_FLAG_LOGGING on a copy of the
flags of the split extent map.

Reported-by: Dan Carpenter 
Link: https://lore.kernel.org/linux-btrfs/Y%2FyipSVozUDEZKow@kili/
Fixes: db21370bffbc ("btrfs: drop extent map range more efficiently")
Signed-off-by: Filipe Manana 
Signed-off-by: David Sterba

btrfs: remove no longer used btrfs_next_extent_map()

2022-12-05T17:00:56+00:00

There are no more users of btrfs_next_extent_map(), the previous patch
in the series ("btrfs: search for delalloc more efficiently during
lseek/fiemap") removed the last usage of the function, so delete it.

This change is part of a patchset that has the goal to make performance
better for applications that use lseek's SEEK_HOLE and SEEK_DATA modes to
iterate over the extents of a file. Two examples are the cp program from
coreutils 9.0+ and the tar program (when using its --sparse / -S option).
A sample test and results are listed in the changelog of the last patch
in the series:

  1/9 btrfs: remove leftover setting of EXTENT_UPTODATE state in an inode's io_tree
  2/9 btrfs: add an early exit when searching for delalloc range for lseek/fiemap
  3/9 btrfs: skip unnecessary delalloc searches during lseek/fiemap
  4/9 btrfs: search for delalloc more efficiently during lseek/fiemap
  5/9 btrfs: remove no longer used btrfs_next_extent_map()
  6/9 btrfs: allow passing a cached state record to count_range_bits()
  7/9 btrfs: update stale comment for count_range_bits()
  8/9 btrfs: use cached state when looking for delalloc ranges with fiemap
  9/9 btrfs: use cached state when looking for delalloc ranges with lseek

Reported-by: Wang Yugui 
Link: https://lore.kernel.org/linux-btrfs/20221106073028.71F9.409509F4@e16-tech.com/
Link: https://lore.kernel.org/linux-btrfs/CAL3q7H5NSVicm7nYBJ7x8fFkDpno8z3PYt5aPU43Bajc1H0h1Q@mail.gmail.com/
Signed-off-by: Filipe Manana 
Signed-off-by: David Sterba

btrfs: selftests: remove impossible inline extent at non-zero file offset

2022-12-05T17:00:47+00:00

In our inode-tests.c, we create an inline offset at file offset 5, which
is no longer possible since the introduction of tree-checker.

Thus I don't think we should spend time maintaining some corner cases
which are already ruled out by tree-checker.

So this patch will:

- Change the inline extent to start at file offset 0

  Also change its length to 6 to cover the original length

- Add an extra ASSERT() for btrfs_add_extent_mapping()

  This is to make sure tree-checker is working correctly.

- Update the inode selftest

Signed-off-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: update function comments

2022-12-05T17:00:45+00:00

Update, reformat or reword function comments. This also removes the kdoc
marker so we don't get reports when the function name is missing.

Changes made:

- remove kdoc markers
- reformat the brief description to be a proper sentence
- reword to imperative voice
- align parameter list
- fix typos

Signed-off-by: David Sterba