linux-stable.git/block/bio.c, branch v4.1.26

bio: return EINTR if copying to user space got interrupted

2016-03-04T15:25:43+00:00

[ Upstream commit 2d99b55d378c996b9692a0c93dd25f4ed5d58934 ]

Commit 35dc248383bbab0a7203fca4d722875bc81ef091 introduced a check for
current->mm to see if we have a user space context and only copies data
if we do. Now if an IO gets interrupted by a signal data isn't copied
into user space any more (as we don't have a user space context) but
user space isn't notified about it.

This patch modifies the behaviour to return -EINTR from bio_uncopy_user()
to notify userland that a signal has interrupted the syscall, otherwise
it could lead to a situation where the caller may get a buffer with
no data returned.

This can be reproduced by issuing SG_IO ioctl()s in one thread while
constantly sending signals to it.

Fixes: 35dc248 [SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
Signed-off-by: Johannes Thumshirn 
Signed-off-by: Hannes Reinecke 
Cc: stable@vger.kernel.org # v.3.11+
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: Do a full clone when splitting discard bios

2015-08-03T16:29:07+00:00

commit f3f5da624e0a891c34d8cd513c57f1d9b0c7dadc upstream.

This fixes a data corruption bug when using discard on top of MD linear,
raid0 and raid10 personalities.

Commit 20d0189b1012 "block: Introduce new bio_split()" permits sharing
the bio_vec between the two resulting bios. That is fine for read/write
requests where the bio_vec is immutable. For discards, however, we need
to be able to attach a payload and update the bio_vec so the page can
get mapped to a scatterlist entry. Therefore the bio_vec can not be
shared when splitting discards and we must do a full clone.

Signed-off-by: Martin K. Petersen 
Reported-by: Seunguk Shin 
Tested-by: Seunguk Shin 
Cc: Seunguk Shin 
Cc: Jens Axboe 
Cc: Kent Overstreet 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: rewrite and split __bio_copy_iov()

2015-02-05T16:30:44+00:00

Rewrite __bio_copy_iov using the copy_page_{from,to}_iter helpers, and
split it into two simpler functions.

This commit should contain only literal replacements, without
functional changes.

Cc: Kent Overstreet 
Cc: Jens Axboe 
Cc: Al Viro 
Signed-off-by: Dongsu Park 
[hch: removed the __bio_copy_iov wrapper]
Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: merge __bio_map_user_iov into bio_map_user_iov

2015-02-05T16:30:43+00:00

And also remove the unused bdev argument.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: merge __bio_map_kern into bio_map_kern

2015-02-05T16:30:42+00:00

This saves a little code, and allow to simplify the error handling.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: pass iov_iter to the BLOCK_PC mapping functions

2015-02-05T16:30:40+00:00

Make use of a new interface provided by iov_iter, backed by
scatter-gather list of iovec, instead of the old interface based on
sg_iovec. Also use iov_iter_advance() instead of manual iteration.

This commit should contain only literal replacements, without
functional changes.

Cc: Christoph Hellwig 
Cc: Jens Axboe 
Cc: Doug Gilbert 
Cc: "James E.J. Bottomley" 
Signed-off-by: Kent Overstreet 
[dpark: add more description in commit message]
Signed-off-by: Dongsu Park 
[hch: fixed to do a deep clone of the iov_iter, and to properly use
      the iov_iter direction]
Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: add a helper to free bio bounce buffer pages

2015-02-05T16:30:39+00:00

The code sniplet to walk all bio_vecs and free their pages is opencoded in
way to many places, so factor it into a helper.  Also convert the slightly
more complex cases in bio_kern_endio and __bio_copy_iov where we break
the freeing from an existing loop into a separate one.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: use blk_rq_map_user_iov to implement blk_rq_map_user

2015-02-05T16:30:37+00:00

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: simplify bio_map_kern

2015-02-05T16:30:35+00:00

Just open code the trivial mapping from a kernel virtual address to
a bio instead of going through the complex user address mapping
machinery.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

bio: modify __bio_add_page() to accept pages that don't start a new segment

2014-12-11T16:11:52+00:00

The original behaviour is to refuse to add a new page if the maximum
number of segments has been reached, regardless of the fact the page we
are going to add can be merged into the last segment or not.

Unfortunately, when the system runs under heavy memory fragmentation
conditions, a driver may try to add multiple pages to the last segment.
The original code won't accept them and EBUSY will be reported to
userspace.

This patch modifies the function so it refuses to add a page only in case
the latter starts a new segment and the maximum number of segments has
already been reached.

The bug can be easily reproduced with the st driver:

1) set CONFIG_SCSI_MPT2SAS_MAX_SGE or CONFIG_SCSI_MPT3SAS_MAX_SGE  to 16
2) modprobe st buffer_kbs=1024
3) #dd if=/dev/zero of=/dev/st0 bs=1M count=10
   dd: error writing `/dev/st0': Device or resource busy

Signed-off-by: Maurizio Lombardi 
Signed-off-by: Ming Lei 
Cc: Jet Chen 
Cc: Tomas Henzl 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe