linux.git/fs/btrfs/compression.c, branch v4.10

Btrfs: fix btrfs_decompress_buf2page()

2017-02-11T03:11:03+00:00

If btrfs_decompress_buf2page() is handed a bio with its page in the
middle of the working buffer, then we adjust the offset into the working
buffer. After we copy into the bio, we advance the iterator by the
number of bytes we copied. Then, we have some logic to handle the case
of discontiguous pages and adjust the offset into the working buffer
again. However, if we didn't advance the bio to a new page, we may enter
this case in error, essentially repeating the adjustment that we already
made when we entered the function. The end result is bogus data in the
bio.

Previously, we only checked for this case when we advanced to a new
page, but the conversion to bio iterators changed that. This restores
the old, correct behavior.

A case I saw when testing with zlib was:

    buf_start = 42769
    total_out = 46865
    working_bytes = total_out - buf_start = 4096
    start_byte = 45056

The condition (total_out > start_byte && buf_start < start_byte) is
true, so we adjust the offset:

    buf_offset = start_byte - buf_start = 2287
    working_bytes -= buf_offset = 1809
    current_buf_start = buf_start = 42769

Then, we copy

    bytes = min(bvec.bv_len, PAGE_SIZE - buf_offset, working_bytes) = 1809
    buf_offset += bytes = 4096
    working_bytes -= bytes = 0
    current_buf_start += bytes = 44578

After bio_advance(), we are still in the same page, so start_byte is the
same. Then, we check (total_out > start_byte && current_buf_start < start_byte),
which is true! So, we adjust the values again:

    buf_offset = start_byte - buf_start = 2287
    working_bytes = total_out - start_byte = 1809
    current_buf_start = buf_start + buf_offset = 45056

But note that working_bytes was already zero before this, so we should
have stopped copying.

Fixes: 974b1adc3b10 ("btrfs: use bio iterators for the decompression handlers")
Reported-by: Pat Erley 
Reviewed-by: Chris Mason 
Signed-off-by: Omar Sandoval 
Signed-off-by: Chris Mason 
Reviewed-by: Liu Bo 
Tested-by: Liu Bo

btrfs: take an fs_info directly when the root is not used otherwise

2016-12-06T15:06:59+00:00

There are loads of functions in btrfs that accept a root parameter
but only use it to obtain an fs_info pointer.  Let's convert those to
just accept an fs_info pointer directly.

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

btrfs: root->fs_info cleanup, add fs_info convenience variables

2016-12-06T15:06:59+00:00

In routines where someptr->fs_info is referenced multiple times, we
introduce a convenience variable.  This makes the code considerably
more readable.

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

btrfs: pull node/sector/stripe sizes out of root and into fs_info

2016-12-06T15:06:58+00:00

We track the node sizes per-root, but they never vary from the values
in the superblock.  This patch messes with the 80-column style a bit,
but subsequent patches to factor out root->fs_info into a convenience
variable fix it up again.

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

btrfs: calculate end of bio offset properly

2016-11-30T12:45:20+00:00

Use the bvec offset and len members to prepare for multipage bvecs.

Signed-off-by: Christoph Hellwig 
Signed-off-by: David Sterba

btrfs: use bi_size

2016-11-30T12:45:20+00:00

Instead of using bi_vcnt to calculate it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Omar Sandoval 
Signed-off-by: David Sterba

btrfs: use bio iterators for the decompression handlers

2016-11-30T12:45:19+00:00

Pass the full bio to the decompression routines and use bio iterators
to iterate over the data in the bio.

Signed-off-by: Christoph Hellwig 
Signed-off-by: David Sterba

btrfs: change btrfs_csum_final result param type to u8

2016-11-30T12:45:18+00:00

csum member of struct btrfs_super_block has array type of u8. It makes
sense that function btrfs_csum_final should be also declared to accept
u8 *. I changed the declaration of method void btrfs_csum_final(u32 crc,
char *result); to void btrfs_csum_final(u32 crc, u8 *result);

Signed-off-by: Domagoj Tršan 
[ changed cast to u8 at several call sites ]
Signed-off-by: David Sterba

btrfs: assign error values to the correct bio structs

2016-10-17T21:16:14+00:00

Fixes: 4246a0b63bd8 ("block: add a bi_error field to struct bio")
Signed-off-by: Junjie Mao 
Acked-by: David Sterba 
Cc: stable@vger.kernel.org # 4.3+
Signed-off-by: Linus Torvalds

btrfs: convert pr_* to btrfs_* where possible

2016-09-26T17:37:04+00:00

For many printks, we want to know which file system issued the message.

This patch converts most pr_* calls to use the btrfs_* versions instead.
In some cases, this means adding plumbing to allow call sites access to
an fs_info pointer.

fs/btrfs/check-integrity.c is left alone for another day.

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