<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/fs/f2fs, branch v5.13</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>f2fs: return EINVAL for hole cases in swap file</title>
<updated>2021-05-12T14:38:00+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2021-05-12T14:38:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f395183f9544ba2f56b25938d6ea7042bd873521'/>
<id>f395183f9544ba2f56b25938d6ea7042bd873521</id>
<content type='text'>
This tries to fix xfstests/generic/495.

Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This tries to fix xfstests/generic/495.

Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: avoid swapon failure by giving a warning first</title>
<updated>2021-05-12T03:51:53+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2021-05-11T21:38:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ca298241bc229303ff683db7265a2c625a9c00fe'/>
<id>ca298241bc229303ff683db7265a2c625a9c00fe</id>
<content type='text'>
The final solution can be migrating blocks to form a section-aligned file
internally. Meanwhile, let's ask users to do that when preparing the swap
file initially like:
1) create()
2) ioctl(F2FS_IOC_SET_PIN_FILE)
3) fallocate()

Reported-by: kernel test robot &lt;oliver.sang@intel.com&gt;
Fixes: 36e4d95891ed ("f2fs: check if swapfile is section-alligned")
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The final solution can be migrating blocks to form a section-aligned file
internally. Meanwhile, let's ask users to do that when preparing the swap
file initially like:
1) create()
2) ioctl(F2FS_IOC_SET_PIN_FILE)
3) fallocate()

Reported-by: kernel test robot &lt;oliver.sang@intel.com&gt;
Fixes: 36e4d95891ed ("f2fs: check if swapfile is section-alligned")
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: compress: fix to assign cc.cluster_idx correctly</title>
<updated>2021-05-11T21:48:12+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2021-05-10T09:30:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8bfbfb0ddd706b1ce2e89259ecc45f192c0ec2bf'/>
<id>8bfbfb0ddd706b1ce2e89259ecc45f192c0ec2bf</id>
<content type='text'>
In f2fs_destroy_compress_ctx(), after f2fs_destroy_compress_ctx(),
cc.cluster_idx will be cleared w/ NULL_CLUSTER, f2fs_cluster_blocks()
may check wrong cluster metadata, fix it.

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In f2fs_destroy_compress_ctx(), after f2fs_destroy_compress_ctx(),
cc.cluster_idx will be cleared w/ NULL_CLUSTER, f2fs_cluster_blocks()
may check wrong cluster metadata, fix it.

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: compress: fix race condition of overwrite vs truncate</title>
<updated>2021-05-11T21:48:12+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2021-05-10T09:30:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a949dc5f2c5cfe0c910b664650f45371254c0744'/>
<id>a949dc5f2c5cfe0c910b664650f45371254c0744</id>
<content type='text'>
pos_fsstress testcase complains a panic as belew:

------------[ cut here ]------------
kernel BUG at fs/f2fs/compress.c:1082!
invalid opcode: 0000 [#1] SMP PTI
CPU: 4 PID: 2753477 Comm: kworker/u16:2 Tainted: G           OE     5.12.0-rc1-custom #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
Workqueue: writeback wb_workfn (flush-252:16)
RIP: 0010:prepare_compress_overwrite+0x4c0/0x760 [f2fs]
Call Trace:
 f2fs_prepare_compress_overwrite+0x5f/0x80 [f2fs]
 f2fs_write_cache_pages+0x468/0x8a0 [f2fs]
 f2fs_write_data_pages+0x2a4/0x2f0 [f2fs]
 do_writepages+0x38/0xc0
 __writeback_single_inode+0x44/0x2a0
 writeback_sb_inodes+0x223/0x4d0
 __writeback_inodes_wb+0x56/0xf0
 wb_writeback+0x1dd/0x290
 wb_workfn+0x309/0x500
 process_one_work+0x220/0x3c0
 worker_thread+0x53/0x420
 kthread+0x12f/0x150
 ret_from_fork+0x22/0x30

The root cause is truncate() may race with overwrite as below,
so that one reference count left in page can not guarantee the
page attaching in mapping tree all the time, after truncation,
later find_lock_page() may return NULL pointer.

- prepare_compress_overwrite
 - f2fs_pagecache_get_page
 - unlock_page
					- f2fs_setattr
					 - truncate_setsize
					  - truncate_inode_page
					   - delete_from_page_cache
 - find_lock_page

Fix this by avoiding referencing updated page.

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
pos_fsstress testcase complains a panic as belew:

------------[ cut here ]------------
kernel BUG at fs/f2fs/compress.c:1082!
invalid opcode: 0000 [#1] SMP PTI
CPU: 4 PID: 2753477 Comm: kworker/u16:2 Tainted: G           OE     5.12.0-rc1-custom #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
Workqueue: writeback wb_workfn (flush-252:16)
RIP: 0010:prepare_compress_overwrite+0x4c0/0x760 [f2fs]
Call Trace:
 f2fs_prepare_compress_overwrite+0x5f/0x80 [f2fs]
 f2fs_write_cache_pages+0x468/0x8a0 [f2fs]
 f2fs_write_data_pages+0x2a4/0x2f0 [f2fs]
 do_writepages+0x38/0xc0
 __writeback_single_inode+0x44/0x2a0
 writeback_sb_inodes+0x223/0x4d0
 __writeback_inodes_wb+0x56/0xf0
 wb_writeback+0x1dd/0x290
 wb_workfn+0x309/0x500
 process_one_work+0x220/0x3c0
 worker_thread+0x53/0x420
 kthread+0x12f/0x150
 ret_from_fork+0x22/0x30

The root cause is truncate() may race with overwrite as below,
so that one reference count left in page can not guarantee the
page attaching in mapping tree all the time, after truncation,
later find_lock_page() may return NULL pointer.

- prepare_compress_overwrite
 - f2fs_pagecache_get_page
 - unlock_page
					- f2fs_setattr
					 - truncate_setsize
					  - truncate_inode_page
					   - delete_from_page_cache
 - find_lock_page

Fix this by avoiding referencing updated page.

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: compress: fix to free compress page correctly</title>
<updated>2021-05-11T21:48:12+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2021-05-06T09:00:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a12cc5b423d4f36dc1a1ea3911e49cf9dff43898'/>
<id>a12cc5b423d4f36dc1a1ea3911e49cf9dff43898</id>
<content type='text'>
In error path of f2fs_write_compressed_pages(), it needs to call
f2fs_compress_free_page() to release temporary page.

Fixes: 5e6bbde95982 ("f2fs: introduce mempool for {,de}compress intermediate page allocation")
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In error path of f2fs_write_compressed_pages(), it needs to call
f2fs_compress_free_page() to release temporary page.

Fixes: 5e6bbde95982 ("f2fs: introduce mempool for {,de}compress intermediate page allocation")
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: support iflag change given the mask</title>
<updated>2021-05-11T21:48:11+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2021-05-06T19:11:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a753103909a7e3d22147505d944da3d20759e1a5'/>
<id>a753103909a7e3d22147505d944da3d20759e1a5</id>
<content type='text'>
In f2fs_fileattr_set(),

	if (!fa-&gt;flags_valid)
		mask &amp;= FS_COMMON_FL;

In this case, we can set supported flags by mask only instead of BUG_ON.

/* Flags shared betwen flags/xflags */
	(FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \
	 FS_NODUMP_FL |	FS_NOATIME_FL | FS_DAX_FL | \
	 FS_PROJINHERIT_FL)

Fixes: 9b1bb01c8ae7 ("f2fs: convert to fileattr")
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In f2fs_fileattr_set(),

	if (!fa-&gt;flags_valid)
		mask &amp;= FS_COMMON_FL;

In this case, we can set supported flags by mask only instead of BUG_ON.

/* Flags shared betwen flags/xflags */
	(FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \
	 FS_NODUMP_FL |	FS_NOATIME_FL | FS_DAX_FL | \
	 FS_PROJINHERIT_FL)

Fixes: 9b1bb01c8ae7 ("f2fs: convert to fileattr")
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>f2fs: avoid null pointer access when handling IPU error</title>
<updated>2021-05-11T21:48:07+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2021-05-10T04:53:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=349c4d6c75d74b62d8e39913b40bd06117b85e4a'/>
<id>349c4d6c75d74b62d8e39913b40bd06117b85e4a</id>
<content type='text'>
 Unable to handle kernel NULL pointer dereference at virtual address 000000000000001a
 pc : f2fs_inplace_write_data+0x144/0x208
 lr : f2fs_inplace_write_data+0x134/0x208
 Call trace:
  f2fs_inplace_write_data+0x144/0x208
  f2fs_do_write_data_page+0x270/0x770
  f2fs_write_single_data_page+0x47c/0x830
  __f2fs_write_data_pages+0x444/0x98c
  f2fs_write_data_pages.llvm.16514453770497736882+0x2c/0x38
  do_writepages+0x58/0x118
  __writeback_single_inode+0x44/0x300
  writeback_sb_inodes+0x4b8/0x9c8
  wb_writeback+0x148/0x42c
  wb_do_writeback+0xc8/0x390
  wb_workfn+0xb0/0x2f4
  process_one_work+0x1fc/0x444
  worker_thread+0x268/0x4b4
  kthread+0x13c/0x158
  ret_from_fork+0x10/0x18

Fixes: 955772787667 ("f2fs: drop inplace IO if fs status is abnormal")
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
 Unable to handle kernel NULL pointer dereference at virtual address 000000000000001a
 pc : f2fs_inplace_write_data+0x144/0x208
 lr : f2fs_inplace_write_data+0x134/0x208
 Call trace:
  f2fs_inplace_write_data+0x144/0x208
  f2fs_do_write_data_page+0x270/0x770
  f2fs_write_single_data_page+0x47c/0x830
  __f2fs_write_data_pages+0x444/0x98c
  f2fs_write_data_pages.llvm.16514453770497736882+0x2c/0x38
  do_writepages+0x58/0x118
  __writeback_single_inode+0x44/0x300
  writeback_sb_inodes+0x4b8/0x9c8
  wb_writeback+0x148/0x42c
  wb_do_writeback+0xc8/0x390
  wb_workfn+0xb0/0x2f4
  process_one_work+0x1fc/0x444
  worker_thread+0x268/0x4b4
  kthread+0x13c/0x158
  ret_from_fork+0x10/0x18

Fixes: 955772787667 ("f2fs: drop inplace IO if fs status is abnormal")
Reviewed-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'f2fs-for-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs</title>
<updated>2021-05-05T01:03:38+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-05-05T01:03:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d0195c7d7af6a456c37f4b4b2df5528f10714482'/>
<id>d0195c7d7af6a456c37f4b4b2df5528f10714482</id>
<content type='text'>
Pull f2fs updates from Jaegeuk Kim:
 "In this round, we added a new mount option, "checkpoint_merge", which
  introduces a kernel thread dealing with the f2fs checkpoints. Once we
  start to manage the IO priority along with blk-cgroup, the checkpoint
  operation can be processed in a lower priority under the process
  context. Since the checkpoint holds all the filesystem operations, we
  give a higher priority to the checkpoint thread all the time.

  Enhancements:
   - introduce gc_merge mount option to introduce a checkpoint thread
   - improve to run discard thread efficiently
   - allow modular compression algorithms
   - expose # of overprivision segments to sysfs
   - expose runtime compression stat to sysfs

  Bug fixes:
   - fix OOB memory access by the node id lookup
   - avoid touching checkpointed data in the checkpoint-disabled mode
   - fix the resizing flow to avoid kernel panic and race conditions
   - fix block allocation issues on pinned files
   - address some swapfile issues
   - fix hugtask problem and kernel panic during atomic write operations
   - don't start checkpoint thread in RO

  And, we've cleaned up some kernel coding style and build warnings. In
  addition, we fixed some minor race conditions and error handling
  routines"

* tag 'f2fs-for-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (48 commits)
  f2fs: drop inplace IO if fs status is abnormal
  f2fs: compress: remove unneed check condition
  f2fs: clean up left deprecated IO trace codes
  f2fs: avoid using native allocate_segment_by_default()
  f2fs: remove unnecessary struct declaration
  f2fs: fix to avoid NULL pointer dereference
  f2fs: avoid duplicated codes for cleanup
  f2fs: document: add description about compressed space handling
  f2fs: clean up build warnings
  f2fs: fix the periodic wakeups of discard thread
  f2fs: fix to avoid accessing invalid fio in f2fs_allocate_data_block()
  f2fs: fix to avoid GC/mmap race with f2fs_truncate()
  f2fs: set checkpoint_merge by default
  f2fs: Fix a hungtask problem in atomic write
  f2fs: fix to restrict mount condition on readonly block device
  f2fs: introduce gc_merge mount option
  f2fs: fix to cover __allocate_new_section() with curseg_lock
  f2fs: fix wrong alloc_type in f2fs_do_replace_block
  f2fs: delete empty compress.h
  f2fs: fix a typo in inode.c
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull f2fs updates from Jaegeuk Kim:
 "In this round, we added a new mount option, "checkpoint_merge", which
  introduces a kernel thread dealing with the f2fs checkpoints. Once we
  start to manage the IO priority along with blk-cgroup, the checkpoint
  operation can be processed in a lower priority under the process
  context. Since the checkpoint holds all the filesystem operations, we
  give a higher priority to the checkpoint thread all the time.

  Enhancements:
   - introduce gc_merge mount option to introduce a checkpoint thread
   - improve to run discard thread efficiently
   - allow modular compression algorithms
   - expose # of overprivision segments to sysfs
   - expose runtime compression stat to sysfs

  Bug fixes:
   - fix OOB memory access by the node id lookup
   - avoid touching checkpointed data in the checkpoint-disabled mode
   - fix the resizing flow to avoid kernel panic and race conditions
   - fix block allocation issues on pinned files
   - address some swapfile issues
   - fix hugtask problem and kernel panic during atomic write operations
   - don't start checkpoint thread in RO

  And, we've cleaned up some kernel coding style and build warnings. In
  addition, we fixed some minor race conditions and error handling
  routines"

* tag 'f2fs-for-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (48 commits)
  f2fs: drop inplace IO if fs status is abnormal
  f2fs: compress: remove unneed check condition
  f2fs: clean up left deprecated IO trace codes
  f2fs: avoid using native allocate_segment_by_default()
  f2fs: remove unnecessary struct declaration
  f2fs: fix to avoid NULL pointer dereference
  f2fs: avoid duplicated codes for cleanup
  f2fs: document: add description about compressed space handling
  f2fs: clean up build warnings
  f2fs: fix the periodic wakeups of discard thread
  f2fs: fix to avoid accessing invalid fio in f2fs_allocate_data_block()
  f2fs: fix to avoid GC/mmap race with f2fs_truncate()
  f2fs: set checkpoint_merge by default
  f2fs: Fix a hungtask problem in atomic write
  f2fs: fix to restrict mount condition on readonly block device
  f2fs: introduce gc_merge mount option
  f2fs: fix to cover __allocate_new_section() with curseg_lock
  f2fs: fix wrong alloc_type in f2fs_do_replace_block
  f2fs: delete empty compress.h
  f2fs: fix a typo in inode.c
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs</title>
<updated>2021-05-02T16:14:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-05-02T16:14:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=27787ba3fa4904422b3928b898d1bd3d74d98bea'/>
<id>27787ba3fa4904422b3928b898d1bd3d74d98bea</id>
<content type='text'>
Pull misc vfs updates from Al Viro:
 "Assorted stuff all over the place"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  useful constants: struct qstr for ".."
  hostfs_open(): don't open-code file_dentry()
  whack-a-mole: kill strlen_user() (again)
  autofs: should_expire() argument is guaranteed to be positive
  apparmor:match_mn() - constify devpath argument
  buffer: a small optimization in grow_buffers
  get rid of autofs_getpath()
  constify dentry argument of dentry_path()/dentry_path_raw()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull misc vfs updates from Al Viro:
 "Assorted stuff all over the place"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  useful constants: struct qstr for ".."
  hostfs_open(): don't open-code file_dentry()
  whack-a-mole: kill strlen_user() (again)
  autofs: should_expire() argument is guaranteed to be positive
  apparmor:match_mn() - constify devpath argument
  buffer: a small optimization in grow_buffers
  get rid of autofs_getpath()
  constify dentry argument of dentry_path()/dentry_path_raw()
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'netfs-lib-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs</title>
<updated>2021-04-27T20:08:12+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2021-04-27T20:08:12+00:00</published>
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<id>820c4bae40cb56466cfed6409e00d0f5165a990c</id>
<content type='text'>
Pull network filesystem helper library updates from David Howells:
 "Here's a set of patches for 5.13 to begin the process of overhauling
  the local caching API for network filesystems. This set consists of
  two parts:

  (1) Add a helper library to handle the new VM readahead interface.

      This is intended to be used unconditionally by the filesystem
      (whether or not caching is enabled) and provides a common
      framework for doing caching, transparent huge pages and, in the
      future, possibly fscrypt and read bandwidth maximisation. It also
      allows the netfs and the cache to align, expand and slice up a
      read request from the VM in various ways; the netfs need only
      provide a function to read a stretch of data to the pagecache and
      the helper takes care of the rest.

  (2) Add an alternative fscache/cachfiles I/O API that uses the kiocb
      facility to do async DIO to transfer data to/from the netfs's
      pages, rather than using readpage with wait queue snooping on one
      side and vfs_write() on the other. It also uses less memory, since
      it doesn't do buffered I/O on the backing file.

      Note that this uses SEEK_HOLE/SEEK_DATA to locate the data
      available to be read from the cache. Whilst this is an improvement
      from the bmap interface, it still has a problem with regard to a
      modern extent-based filesystem inserting or removing bridging
      blocks of zeros. Fixing that requires a much greater overhaul.

  This is a step towards overhauling the fscache API. The change is
  opt-in on the part of the network filesystem. A netfs should not try
  to mix the old and the new API because of conflicting ways of handling
  pages and the PG_fscache page flag and because it would be mixing DIO
  with buffered I/O. Further, the helper library can't be used with the
  old API.

  This does not change any of the fscache cookie handling APIs or the
  way invalidation is done at this time.

  In the near term, I intend to deprecate and remove the old I/O API
  (fscache_allocate_page{,s}(), fscache_read_or_alloc_page{,s}(),
  fscache_write_page() and fscache_uncache_page()) and eventually
  replace most of fscache/cachefiles with something simpler and easier
  to follow.

  This patchset contains the following parts:

   - Some helper patches, including provision of an ITER_XARRAY iov
     iterator and a function to do readahead expansion.

   - Patches to add the netfs helper library.

   - A patch to add the fscache/cachefiles kiocb API.

   - A pair of patches to fix some review issues in the ITER_XARRAY and
     read helpers as spotted by Al and Willy.

  Jeff Layton has patches to add support in Ceph for this that he
  intends for this merge window. I have a set of patches to support AFS
  that I will post a separate pull request for.

  With this, AFS without a cache passes all expected xfstests; with a
  cache, there's an extra failure, but that's also there before these
  patches. Fixing that probably requires a greater overhaul. Ceph also
  passes the expected tests.

  I also have patches in a separate branch to tidy up the handling of
  PG_fscache/PG_private_2 and their contribution to page refcounting in
  the core kernel here, but I haven't included them in this set and will
  route them separately"

Link: https://lore.kernel.org/lkml/3779937.1619478404@warthog.procyon.org.uk/

* tag 'netfs-lib-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  netfs: Miscellaneous fixes
  iov_iter: Four fixes for ITER_XARRAY
  fscache, cachefiles: Add alternate API to use kiocb for read/write to cache
  netfs: Add a tracepoint to log failures that would be otherwise unseen
  netfs: Define an interface to talk to a cache
  netfs: Add write_begin helper
  netfs: Gather stats
  netfs: Add tracepoints
  netfs: Provide readahead and readpage netfs helpers
  netfs, mm: Add set/end/wait_on_page_fscache() aliases
  netfs, mm: Move PG_fscache helper funcs to linux/netfs.h
  netfs: Documentation for helper library
  netfs: Make a netfs helper module
  mm: Implement readahead_control pageset expansion
  mm/readahead: Handle ractl nr_pages being modified
  fs: Document file_ra_state
  mm/filemap: Pass the file_ra_state in the ractl
  mm: Add set/end/wait functions for PG_private_2
  iov_iter: Add ITER_XARRAY
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<pre>
Pull network filesystem helper library updates from David Howells:
 "Here's a set of patches for 5.13 to begin the process of overhauling
  the local caching API for network filesystems. This set consists of
  two parts:

  (1) Add a helper library to handle the new VM readahead interface.

      This is intended to be used unconditionally by the filesystem
      (whether or not caching is enabled) and provides a common
      framework for doing caching, transparent huge pages and, in the
      future, possibly fscrypt and read bandwidth maximisation. It also
      allows the netfs and the cache to align, expand and slice up a
      read request from the VM in various ways; the netfs need only
      provide a function to read a stretch of data to the pagecache and
      the helper takes care of the rest.

  (2) Add an alternative fscache/cachfiles I/O API that uses the kiocb
      facility to do async DIO to transfer data to/from the netfs's
      pages, rather than using readpage with wait queue snooping on one
      side and vfs_write() on the other. It also uses less memory, since
      it doesn't do buffered I/O on the backing file.

      Note that this uses SEEK_HOLE/SEEK_DATA to locate the data
      available to be read from the cache. Whilst this is an improvement
      from the bmap interface, it still has a problem with regard to a
      modern extent-based filesystem inserting or removing bridging
      blocks of zeros. Fixing that requires a much greater overhaul.

  This is a step towards overhauling the fscache API. The change is
  opt-in on the part of the network filesystem. A netfs should not try
  to mix the old and the new API because of conflicting ways of handling
  pages and the PG_fscache page flag and because it would be mixing DIO
  with buffered I/O. Further, the helper library can't be used with the
  old API.

  This does not change any of the fscache cookie handling APIs or the
  way invalidation is done at this time.

  In the near term, I intend to deprecate and remove the old I/O API
  (fscache_allocate_page{,s}(), fscache_read_or_alloc_page{,s}(),
  fscache_write_page() and fscache_uncache_page()) and eventually
  replace most of fscache/cachefiles with something simpler and easier
  to follow.

  This patchset contains the following parts:

   - Some helper patches, including provision of an ITER_XARRAY iov
     iterator and a function to do readahead expansion.

   - Patches to add the netfs helper library.

   - A patch to add the fscache/cachefiles kiocb API.

   - A pair of patches to fix some review issues in the ITER_XARRAY and
     read helpers as spotted by Al and Willy.

  Jeff Layton has patches to add support in Ceph for this that he
  intends for this merge window. I have a set of patches to support AFS
  that I will post a separate pull request for.

  With this, AFS without a cache passes all expected xfstests; with a
  cache, there's an extra failure, but that's also there before these
  patches. Fixing that probably requires a greater overhaul. Ceph also
  passes the expected tests.

  I also have patches in a separate branch to tidy up the handling of
  PG_fscache/PG_private_2 and their contribution to page refcounting in
  the core kernel here, but I haven't included them in this set and will
  route them separately"

Link: https://lore.kernel.org/lkml/3779937.1619478404@warthog.procyon.org.uk/

* tag 'netfs-lib-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  netfs: Miscellaneous fixes
  iov_iter: Four fixes for ITER_XARRAY
  fscache, cachefiles: Add alternate API to use kiocb for read/write to cache
  netfs: Add a tracepoint to log failures that would be otherwise unseen
  netfs: Define an interface to talk to a cache
  netfs: Add write_begin helper
  netfs: Gather stats
  netfs: Add tracepoints
  netfs: Provide readahead and readpage netfs helpers
  netfs, mm: Add set/end/wait_on_page_fscache() aliases
  netfs, mm: Move PG_fscache helper funcs to linux/netfs.h
  netfs: Documentation for helper library
  netfs: Make a netfs helper module
  mm: Implement readahead_control pageset expansion
  mm/readahead: Handle ractl nr_pages being modified
  fs: Document file_ra_state
  mm/filemap: Pass the file_ra_state in the ractl
  mm: Add set/end/wait functions for PG_private_2
  iov_iter: Add ITER_XARRAY
</pre>
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