Merge tag 'for-6.5/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Update DM crypt to allocate compound pages if possible

 - Fix DM crypt target's crypt_ctr_cipher_new return value on invalid
   AEAD cipher

 - Fix DM flakey testing target's write bio corruption feature to
   corrupt the data of a cloned bio instead of the original

 - Add random_read_corrupt and random_write_corrupt features to DM
   flakey target

 - Fix ABBA deadlock in DM thin metadata by resetting associated bufio
   client rather than destroying and recreating it

 - A couple other small DM thinp cleanups

 - Update DM core to support disabling block core IO stats accounting
   and optimize away code that isn't needed if stats are disabled

 - Other small DM core cleanups

 - Improve DM integrity target to not require so much memory on 32 bit
   systems. Also only allocate the recalculate buffer as needed (and
   increasingly reduce its size on allocation failure)

 - Update DM integrity to use %*ph for printing hexdump of a small
   buffer. Also update DM integrity documentation

 - Various DM core ioctl interface hardening. Now more careful about
   alignment of structures and processing of input passed to the kernel
   from userspace.

   Also disallow the creation of DM devices named "control", "." or ".."

 - Eliminate GFP_NOIO workarounds for __vmalloc and kvmalloc in DM
   core's ioctl and bufio code

* tag 'for-6.5/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (28 commits)
  dm: get rid of GFP_NOIO workarounds for __vmalloc and kvmalloc
  dm integrity: scale down the recalculate buffer if memory allocation fails
  dm integrity: only allocate recalculate buffer when needed
  dm integrity: reduce vmalloc space footprint on 32-bit architectures
  dm ioctl: Refuse to create device named "." or ".."
  dm ioctl: Refuse to create device named "control"
  dm ioctl: Avoid double-fetch of version
  dm ioctl: structs and parameter strings must not overlap
  dm ioctl: Avoid pointer arithmetic overflow
  dm ioctl: Check dm_target_spec is sufficiently aligned
  Documentation: dm-integrity: Document an example of how the tunables relate.
  Documentation: dm-integrity: Document default values.
  Documentation: dm-integrity: Document the meaning of "buffer".
  Documentation: dm-integrity: Fix minor grammatical error.
  dm integrity: Use %*ph for printing hexdump of a small buffer
  dm thin: disable discards for thin-pool if no_discard_passdown
  dm: remove stale/redundant dm_internal_{suspend,resume} prototypes in dm.h
  dm: skip dm-stats work in alloc_io() unless needed
  dm: avoid needless dm_io access if all IO accounting is disabled
  dm: support turning off block-core's io stats accounting
  ...

2 files changed, 37 insertions, 16 deletions

diff --git a/Documentation/admin-guide/device-mapper/dm-flakey.rst b/Documentation/admin-guide/device-mapper/dm-flakey.rst
index f7104c01b0f7..f967c5fea219 100644
--- a/Documentation/admin-guide/device-mapper/dm-flakey.rst
+++ b/Documentation/admin-guide/device-mapper/dm-flakey.rst
@@ -67,6 +67,16 @@ Optional feature parameters:
 	Perform the replacement only if bio->bi_opf has all the
 	selected flags set.
 
+  random_read_corrupt <probability>
+	During <down interval>, replace random byte in a read bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+  random_write_corrupt <probability>
+	During <down interval>, replace random byte in a write bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
 Examples:
 
 Replaces the 32nd byte of READ bios with the value 1::
diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst
index 8db172efa272..d8a5f14d0e3c 100644
--- a/Documentation/admin-guide/device-mapper/dm-integrity.rst
+++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst
@@ -25,7 +25,7 @@ mode it calculates and verifies the integrity tag internally. In this
 mode, the dm-integrity target can be used to detect silent data
 corruption on the disk or in the I/O path.
 
-There's an alternate mode of operation where dm-integrity uses bitmap
+There's an alternate mode of operation where dm-integrity uses a bitmap
 instead of a journal. If a bit in the bitmap is 1, the corresponding
 region's data and integrity tags are not synchronized - if the machine
 crashes, the unsynchronized regions will be recalculated. The bitmap mode
@@ -38,6 +38,15 @@ the device. But it will only format the device if the superblock contains
 zeroes. If the superblock is neither valid nor zeroed, the dm-integrity
 target can't be loaded.
 
+Accesses to the on-disk metadata area containing checksums (aka tags) are
+buffered using dm-bufio. When an access to any given metadata area
+occurs, each unique metadata area gets its own buffer(s). The buffer size
+is capped at the size of the metadata area, but may be smaller, thereby
+requiring multiple buffers to represent the full metadata area. A smaller
+buffer size will produce a smaller resulting read/write operation to the
+metadata area for small reads/writes. The metadata is still read even in
+a full write to the data covered by a single buffer.
+
 To use the target for the first time:
 
 1. overwrite the superblock with zeroes
@@ -93,7 +102,7 @@ journal_sectors:number
 	device. If the device is already formatted, the value from the
 	superblock is used.
 
-interleave_sectors:number
+interleave_sectors:number (default 32768)
 	The number of interleaved sectors. This values is rounded down to
 	a power of two. If the device is already formatted, the value from
 	the superblock is used.
@@ -102,20 +111,16 @@ meta_device:device
 	Don't interleave the data and metadata on the device. Use a
 	separate device for metadata.
 
-buffer_sectors:number
-	The number of sectors in one buffer. The value is rounded down to
-	a power of two.
-
-	The tag area is accessed using buffers, the buffer size is
-	configurable. The large buffer size means that the I/O size will
-	be larger, but there could be less I/Os issued.
+buffer_sectors:number (default 128)
+	The number of sectors in one metadata buffer. The value is rounded
+	down to a power of two.
 
-journal_watermark:number
+journal_watermark:number (default 50)
 	The journal watermark in percents. When the size of the journal
 	exceeds this watermark, the thread that flushes the journal will
 	be started.
 
-commit_time:number
+commit_time:number (default 10000)
 	Commit time in milliseconds. When this time passes, the journal is
 	written. The journal is also written immediately if the FLUSH
 	request is received.
@@ -163,11 +168,10 @@ journal_mac:algorithm(:key)	(the key is optional)
 	the journal. Thus, modified sector number would be detected at
 	this stage.
 
-block_size:number
-	The size of a data block in bytes.  The larger the block size the
+block_size:number (default 512)
+	The size of a data block in bytes. The larger the block size the
 	less overhead there is for per-block integrity metadata.
-	Supported values are 512, 1024, 2048 and 4096 bytes.  If not
-	specified the default block size is 512 bytes.
+	Supported values are 512, 1024, 2048 and 4096 bytes.
 
 sectors_per_bit:number
 	In the bitmap mode, this parameter specifies the number of
@@ -209,6 +213,12 @@ table and swap the tables with suspend and resume). The other arguments
 should not be changed when reloading the target because the layout of disk
 data depend on them and the reloaded target would be non-functional.
 
+For example, on a device using the default interleave_sectors of 32768, a
+block_size of 512, and an internal_hash of crc32c with a tag size of 4
+bytes, it will take 128 KiB of tags to track a full data area, requiring
+256 sectors of metadata per data area. With the default buffer_sectors of
+128, that means there will be 2 buffers per metadata area, or 2 buffers
+per 16 MiB of data.
 
 Status line:
 
@@ -286,7 +296,8 @@ The layout of the formatted block device:
     Each run contains:
 
 	* tag area - it contains integrity tags. There is one tag for each
-	  sector in the data area
+	  sector in the data area. The size of this area is always 4KiB or
+	  greater.
 	* data area - it contains data sectors. The number of data sectors
 	  in one run must be a power of two. log2 of this value is stored
 	  in the superblock.