Merge tag 'f2fs-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

Pull f2fs updates from Jaegeuk Kim:
 "In this cycle, we've applied relatively small number of patches which
  fix subtle corner cases mainly, while introducing a new mount option
  to be able to fragment the disk intentionally for performance tests.

  Enhancements:

   - add a mount option to fragmente on-disk layout to understand the
     performance

   - support direct IO for multi-partitions

   - add a fault injection of dquot_initialize

  Bug fixes:

   - address some lockdep complaints

   - fix a deadlock issue with quota

   - fix a memory tuning condition

   - fix compression condition to improve the ratio

   - fix disabling compression on the non-empty compressed file

   - invalidate cached pages before IPU/DIO writes

  And, we've added some minor clean-ups as usual"

* tag 'f2fs-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
  f2fs: fix UAF in f2fs_available_free_memory
  f2fs: invalidate META_MAPPING before IPU/DIO write
  f2fs: support fault injection for dquot_initialize()
  f2fs: fix incorrect return value in f2fs_sanity_check_ckpt()
  f2fs: compress: disallow disabling compress on non-empty compressed file
  f2fs: compress: fix overwrite may reduce compress ratio unproperly
  f2fs: multidevice: support direct IO
  f2fs: introduce fragment allocation mode mount option
  f2fs: replace snprintf in show functions with sysfs_emit
  f2fs: include non-compressed blocks in compr_written_block
  f2fs: fix wrong condition to trigger background checkpoint correctly
  f2fs: fix to use WHINT_MODE
  f2fs: fix up f2fs_lookup tracepoints
  f2fs: set SBI_NEED_FSCK flag when inconsistent node block found
  f2fs: introduce excess_dirty_threshold()
  f2fs: avoid attaching SB_ACTIVE flag during mount
  f2fs: quota: fix potential deadlock
  f2fs: should use GFP_NOFS for directory inodes

2 files changed, 35 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index f627e705e663..b268e3e18b4a 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -512,3 +512,19 @@ Date:		July 2021
 Contact:	"Daeho Jeong" <daehojeong@google.com>
 Description:	You can	control the multiplier value of	bdi device readahead window size
 		between 2 (default) and 256 for POSIX_FADV_SEQUENTIAL advise option.
+
+What:		/sys/fs/f2fs/<disk>/max_fragment_chunk
+Date:		August 2021
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	With "mode=fragment:block" mount options, we can scatter block allocation.
+		f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole
+		in the length of 1..<max_fragment_hole> by turns. This value can be set
+		between 1..512 and the default value is 4.
+
+What:		/sys/fs/f2fs/<disk>/max_fragment_hole
+Date:		August 2021
+Contact:	"Daeho Jeong" <daehojeong@google.com>
+Description:	With "mode=fragment:block" mount options, we can scatter block allocation.
+		f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole
+		in the length of 1..<max_fragment_hole> by turns. This value can be set
+		between 1..512 and the default value is 4.
diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index 6f3c6e91346d..d7b84695f56a 100644
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -197,10 +197,29 @@ fault_type=%d		 Support configuring fault injection type, should be
 			 FAULT_DISCARD		  0x000002000
 			 FAULT_WRITE_IO		  0x000004000
 			 FAULT_SLAB_ALLOC	  0x000008000
+			 FAULT_DQUOT_INIT	  0x000010000
 			 ===================	  ===========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random
 			 writes towards main area.
+			 "fragment:segment" and "fragment:block" are newly added here.
+			 These are developer options for experiments to simulate filesystem
+			 fragmentation/after-GC situation itself. The developers use these
+			 modes to understand filesystem fragmentation/after-GC condition well,
+			 and eventually get some insights to handle them better.
+			 In "fragment:segment", f2fs allocates a new segment in ramdom
+			 position. With this, we can simulate the after-GC condition.
+			 In "fragment:block", we can scatter block allocation with
+			 "max_fragment_chunk" and "max_fragment_hole" sysfs nodes.
+			 We added some randomness to both chunk and hole size to make
+			 it close to realistic IO pattern. So, in this mode, f2fs will allocate
+			 1..<max_fragment_chunk> blocks in a chunk and make a hole in the
+			 length of 1..<max_fragment_hole> by turns. With this, the newly
+			 allocated blocks will be scattered throughout the whole partition.
+			 Note that "fragment:block" implicitly enables "fragment:segment"
+			 option for more randomness.
+			 Please, use these options for your experiments and we strongly
+			 recommend to re-format the filesystem after using these options.
 io_bits=%u		 Set the bit size of write IO requests. It should be set
 			 with "mode=lfs".
 usrquota		 Enable plain user disk quota accounting.