<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include/linux/fs.h, branch v5.5.8</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>Merge tag 'xfs-5.5-merge-16' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux</title>
<updated>2019-12-02T22:46:22+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-12-02T22:46:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=97eeb4d9d755605385fa329da9afa38729f3413c'/>
<id>97eeb4d9d755605385fa329da9afa38729f3413c</id>
<content type='text'>
Pull XFS updates from Darrick Wong:
 "For this release, we changed quite a few things.

  Highlights:

   - Fixed some long tail latency problems in the block allocator

   - Removed some long deprecated (and for the past several years no-op)
     mount options and ioctls

   - Strengthened the extended attribute and directory verifiers

   - Audited and fixed all the places where we could return EFSCORRUPTED
     without logging anything

   - Refactored the old SGI space allocation ioctls to make the
     equivalent fallocate calls

   - Fixed a race between fallocate and directio

   - Fixed an integer overflow when files have more than a few
     billion(!) extents

   - Fixed a longstanding bug where quota accounting could be incorrect
     when performing unwritten extent conversion on a freshly mounted fs

   - Fixed various complaints in scrub about soft lockups and
     unresponsiveness to signals

   - De-vtable'd the directory handling code, which should make it
     faster

   - Converted to the new mount api, for better or for worse

   - Cleaned up some memory leaks

  and quite a lot of other smaller fixes and cleanups.

  A more detailed summary:

   - Fill out the build string

   - Prevent inode fork extent count overflows

   - Refactor the allocator to reduce long tail latency

   - Rework incore log locking a little to reduce spinning

   - Break up the xfs_iomap_begin functions into smaller more cohesive
     parts

   - Fix allocation alignment being dropped too early when the
     allocation request is for more blocks than an AG is large

   - Other small cleanups

   - Clean up file buftarg retrieval helpers

   - Hoist the resvsp and unresvsp ioctls to the vfs

   - Remove the undocumented biosize mount option, since it has never
     been mentioned as existing or supported on linux

   - Clean up some of the mount option printing and parsing

   - Enhance attr leaf verifier to check block structure

   - Check dirent and attr names for invalid characters before passing
     them to the vfs

   - Refactor open-coded bmbt walking

   - Fix a few places where we return EIO instead of EFSCORRUPTED after
     failing metadata sanity checks

   - Fix a synchronization problem between fallocate and aio dio
     corrupting the file length

   - Clean up various loose ends in the iomap and bmap code

   - Convert to the new mount api

   - Make sure we always log something when returning EFSCORRUPTED

   - Fix some problems where long running scrub loops could trigger soft
     lockup warnings and/or fail to exit due to fatal signals pending

   - Fix various Coverity complaints

   - Remove most of the function pointers from the directory code to
     reduce indirection penalties

   - Ensure that dquots are attached to the inode when performing
     unwritten extent conversion after io

   - Deuglify incore projid and crtime types

   - Fix another AGI/AGF locking order deadlock when renaming

   - Clean up some quota typedefs

   - Remove the FSSETDM ioctls which haven't done anything in 20 years

   - Fix some memory leaks when mounting the log fails

   - Fix an underflow when updating an xattr leaf freemap

   - Remove some trivial wrappers

   - Report metadata corruption as an error, not a (potentially) fatal
     assertion

   - Clean up the dir/attr buffer mapping code

   - Allow fatal signals to kill scrub during parent pointer checks"

* tag 'xfs-5.5-merge-16' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (198 commits)
  xfs: allow parent directory scans to be interrupted with fatal signals
  xfs: remove the mappedbno argument to xfs_da_get_buf
  xfs: remove the mappedbno argument to xfs_da_read_buf
  xfs: split xfs_da3_node_read
  xfs: remove the mappedbno argument to xfs_dir3_leafn_read
  xfs: remove the mappedbno argument to xfs_dir3_leaf_read
  xfs: remove the mappedbno argument to xfs_attr3_leaf_read
  xfs: remove the mappedbno argument to xfs_da_reada_buf
  xfs: improve the xfs_dabuf_map calling conventions
  xfs: refactor xfs_dabuf_map
  xfs: simplify mappedbno handling in xfs_da_{get,read}_buf
  xfs: report corruption only as a regular error
  xfs: Remove kmem_zone_free() wrapper
  xfs: Remove kmem_zone_destroy() wrapper
  xfs: Remove slab init wrappers
  xfs: fix attr leaf header freemap.size underflow
  xfs: fix some memory leaks in log recovery
  xfs: fix another missing include
  xfs: remove XFS_IOC_FSSETDM and XFS_IOC_FSSETDM_BY_HANDLE
  xfs: remove duplicated include from xfs_dir2_data.c
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull XFS updates from Darrick Wong:
 "For this release, we changed quite a few things.

  Highlights:

   - Fixed some long tail latency problems in the block allocator

   - Removed some long deprecated (and for the past several years no-op)
     mount options and ioctls

   - Strengthened the extended attribute and directory verifiers

   - Audited and fixed all the places where we could return EFSCORRUPTED
     without logging anything

   - Refactored the old SGI space allocation ioctls to make the
     equivalent fallocate calls

   - Fixed a race between fallocate and directio

   - Fixed an integer overflow when files have more than a few
     billion(!) extents

   - Fixed a longstanding bug where quota accounting could be incorrect
     when performing unwritten extent conversion on a freshly mounted fs

   - Fixed various complaints in scrub about soft lockups and
     unresponsiveness to signals

   - De-vtable'd the directory handling code, which should make it
     faster

   - Converted to the new mount api, for better or for worse

   - Cleaned up some memory leaks

  and quite a lot of other smaller fixes and cleanups.

  A more detailed summary:

   - Fill out the build string

   - Prevent inode fork extent count overflows

   - Refactor the allocator to reduce long tail latency

   - Rework incore log locking a little to reduce spinning

   - Break up the xfs_iomap_begin functions into smaller more cohesive
     parts

   - Fix allocation alignment being dropped too early when the
     allocation request is for more blocks than an AG is large

   - Other small cleanups

   - Clean up file buftarg retrieval helpers

   - Hoist the resvsp and unresvsp ioctls to the vfs

   - Remove the undocumented biosize mount option, since it has never
     been mentioned as existing or supported on linux

   - Clean up some of the mount option printing and parsing

   - Enhance attr leaf verifier to check block structure

   - Check dirent and attr names for invalid characters before passing
     them to the vfs

   - Refactor open-coded bmbt walking

   - Fix a few places where we return EIO instead of EFSCORRUPTED after
     failing metadata sanity checks

   - Fix a synchronization problem between fallocate and aio dio
     corrupting the file length

   - Clean up various loose ends in the iomap and bmap code

   - Convert to the new mount api

   - Make sure we always log something when returning EFSCORRUPTED

   - Fix some problems where long running scrub loops could trigger soft
     lockup warnings and/or fail to exit due to fatal signals pending

   - Fix various Coverity complaints

   - Remove most of the function pointers from the directory code to
     reduce indirection penalties

   - Ensure that dquots are attached to the inode when performing
     unwritten extent conversion after io

   - Deuglify incore projid and crtime types

   - Fix another AGI/AGF locking order deadlock when renaming

   - Clean up some quota typedefs

   - Remove the FSSETDM ioctls which haven't done anything in 20 years

   - Fix some memory leaks when mounting the log fails

   - Fix an underflow when updating an xattr leaf freemap

   - Remove some trivial wrappers

   - Report metadata corruption as an error, not a (potentially) fatal
     assertion

   - Clean up the dir/attr buffer mapping code

   - Allow fatal signals to kill scrub during parent pointer checks"

* tag 'xfs-5.5-merge-16' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (198 commits)
  xfs: allow parent directory scans to be interrupted with fatal signals
  xfs: remove the mappedbno argument to xfs_da_get_buf
  xfs: remove the mappedbno argument to xfs_da_read_buf
  xfs: split xfs_da3_node_read
  xfs: remove the mappedbno argument to xfs_dir3_leafn_read
  xfs: remove the mappedbno argument to xfs_dir3_leaf_read
  xfs: remove the mappedbno argument to xfs_attr3_leaf_read
  xfs: remove the mappedbno argument to xfs_da_reada_buf
  xfs: improve the xfs_dabuf_map calling conventions
  xfs: refactor xfs_dabuf_map
  xfs: simplify mappedbno handling in xfs_da_{get,read}_buf
  xfs: report corruption only as a regular error
  xfs: Remove kmem_zone_free() wrapper
  xfs: Remove kmem_zone_destroy() wrapper
  xfs: Remove slab init wrappers
  xfs: fix attr leaf header freemap.size underflow
  xfs: fix some memory leaks in log recovery
  xfs: fix another missing include
  xfs: remove XFS_IOC_FSSETDM and XFS_IOC_FSSETDM_BY_HANDLE
  xfs: remove duplicated include from xfs_dir2_data.c
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'akpm' (patches from Andrew)</title>
<updated>2019-12-02T04:36:41+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-12-02T04:36:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=596cf45cbf6e4fa7bcb0df33e373a7d062b644b5'/>
<id>596cf45cbf6e4fa7bcb0df33e373a7d062b644b5</id>
<content type='text'>
Merge updates from Andrew Morton:
 "Incoming:

   - a small number of updates to scripts/, ocfs2 and fs/buffer.c

   - most of MM

  I still have quite a lot of material (mostly not MM) staged after
  linux-next due to -next dependencies. I'll send those across next week
  as the preprequisites get merged up"

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (135 commits)
  mm/page_io.c: annotate refault stalls from swap_readpage
  mm/Kconfig: fix trivial help text punctuation
  mm/Kconfig: fix indentation
  mm/memory_hotplug.c: remove __online_page_set_limits()
  mm: fix typos in comments when calling __SetPageUptodate()
  mm: fix struct member name in function comments
  mm/shmem.c: cast the type of unmap_start to u64
  mm: shmem: use proper gfp flags for shmem_writepage()
  mm/shmem.c: make array 'values' static const, makes object smaller
  userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK
  fs/userfaultfd.c: wp: clear VM_UFFD_MISSING or VM_UFFD_WP during userfaultfd_register()
  userfaultfd: wrap the common dst_vma check into an inlined function
  userfaultfd: remove unnecessary WARN_ON() in __mcopy_atomic_hugetlb()
  userfaultfd: use vma_pagesize for all huge page size calculation
  mm/madvise.c: use PAGE_ALIGN[ED] for range checking
  mm/madvise.c: replace with page_size() in madvise_inject_error()
  mm/mmap.c: make vma_merge() comment more easy to understand
  mm/hwpoison-inject: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops
  autonuma: reduce cache footprint when scanning page tables
  autonuma: fix watermark checking in migrate_balanced_pgdat()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Merge updates from Andrew Morton:
 "Incoming:

   - a small number of updates to scripts/, ocfs2 and fs/buffer.c

   - most of MM

  I still have quite a lot of material (mostly not MM) staged after
  linux-next due to -next dependencies. I'll send those across next week
  as the preprequisites get merged up"

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (135 commits)
  mm/page_io.c: annotate refault stalls from swap_readpage
  mm/Kconfig: fix trivial help text punctuation
  mm/Kconfig: fix indentation
  mm/memory_hotplug.c: remove __online_page_set_limits()
  mm: fix typos in comments when calling __SetPageUptodate()
  mm: fix struct member name in function comments
  mm/shmem.c: cast the type of unmap_start to u64
  mm: shmem: use proper gfp flags for shmem_writepage()
  mm/shmem.c: make array 'values' static const, makes object smaller
  userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK
  fs/userfaultfd.c: wp: clear VM_UFFD_MISSING or VM_UFFD_WP during userfaultfd_register()
  userfaultfd: wrap the common dst_vma check into an inlined function
  userfaultfd: remove unnecessary WARN_ON() in __mcopy_atomic_hugetlb()
  userfaultfd: use vma_pagesize for all huge page size calculation
  mm/madvise.c: use PAGE_ALIGN[ED] for range checking
  mm/madvise.c: replace with page_size() in madvise_inject_error()
  mm/mmap.c: make vma_merge() comment more easy to understand
  mm/hwpoison-inject: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops
  autonuma: reduce cache footprint when scanning page tables
  autonuma: fix watermark checking in migrate_balanced_pgdat()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground</title>
<updated>2019-12-01T21:46:15+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-12-01T21:46:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0da522107e5d9c000a4871d52e570912aa1225a2'/>
<id>0da522107e5d9c000a4871d52e570912aa1225a2</id>
<content type='text'>
Pull removal of most of fs/compat_ioctl.c from Arnd Bergmann:
 "As part of the cleanup of some remaining y2038 issues, I came to
  fs/compat_ioctl.c, which still has a couple of commands that need
  support for time64_t.

  In completely unrelated work, I spent time on cleaning up parts of
  this file in the past, moving things out into drivers instead.

  After Al Viro reviewed an earlier version of this series and did a lot
  more of that cleanup, I decided to try to completely eliminate the
  rest of it and move it all into drivers.

  This series incorporates some of Al's work and many patches of my own,
  but in the end stops short of actually removing the last part, which
  is the scsi ioctl handlers. I have patches for those as well, but they
  need more testing or possibly a rewrite"

* tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (42 commits)
  scsi: sd: enable compat ioctls for sed-opal
  pktcdvd: add compat_ioctl handler
  compat_ioctl: move SG_GET_REQUEST_TABLE handling
  compat_ioctl: ppp: move simple commands into ppp_generic.c
  compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t
  compat_ioctl: move PPPIOCSCOMPRESS to ppp_generic
  compat_ioctl: unify copy-in of ppp filters
  tty: handle compat PPP ioctls
  compat_ioctl: move SIOCOUTQ out of compat_ioctl.c
  compat_ioctl: handle SIOCOUTQNSD
  af_unix: add compat_ioctl support
  compat_ioctl: reimplement SG_IO handling
  compat_ioctl: move WDIOC handling into wdt drivers
  fs: compat_ioctl: move FITRIM emulation into file systems
  gfs2: add compat_ioctl support
  compat_ioctl: remove unused convert_in_user macro
  compat_ioctl: remove last RAID handling code
  compat_ioctl: remove /dev/raw ioctl translation
  compat_ioctl: remove PCI ioctl translation
  compat_ioctl: remove joystick ioctl translation
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull removal of most of fs/compat_ioctl.c from Arnd Bergmann:
 "As part of the cleanup of some remaining y2038 issues, I came to
  fs/compat_ioctl.c, which still has a couple of commands that need
  support for time64_t.

  In completely unrelated work, I spent time on cleaning up parts of
  this file in the past, moving things out into drivers instead.

  After Al Viro reviewed an earlier version of this series and did a lot
  more of that cleanup, I decided to try to completely eliminate the
  rest of it and move it all into drivers.

  This series incorporates some of Al's work and many patches of my own,
  but in the end stops short of actually removing the last part, which
  is the scsi ioctl handlers. I have patches for those as well, but they
  need more testing or possibly a rewrite"

* tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (42 commits)
  scsi: sd: enable compat ioctls for sed-opal
  pktcdvd: add compat_ioctl handler
  compat_ioctl: move SG_GET_REQUEST_TABLE handling
  compat_ioctl: ppp: move simple commands into ppp_generic.c
  compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t
  compat_ioctl: move PPPIOCSCOMPRESS to ppp_generic
  compat_ioctl: unify copy-in of ppp filters
  tty: handle compat PPP ioctls
  compat_ioctl: move SIOCOUTQ out of compat_ioctl.c
  compat_ioctl: handle SIOCOUTQNSD
  af_unix: add compat_ioctl support
  compat_ioctl: reimplement SG_IO handling
  compat_ioctl: move WDIOC handling into wdt drivers
  fs: compat_ioctl: move FITRIM emulation into file systems
  gfs2: add compat_ioctl support
  compat_ioctl: remove unused convert_in_user macro
  compat_ioctl: remove last RAID handling code
  compat_ioctl: remove /dev/raw ioctl translation
  compat_ioctl: remove PCI ioctl translation
  compat_ioctl: remove joystick ioctl translation
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>fs/direct-io.c: keep dio_warn_stale_pagecache() when CONFIG_BLOCK=n</title>
<updated>2019-12-01T14:29:18+00:00</updated>
<author>
<name>Konstantin Khlebnikov</name>
<email>khlebnikov@yandex-team.ru</email>
</author>
<published>2019-12-01T01:49:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a92853b6746fe5ffef20a7c30addf6320561e669'/>
<id>a92853b6746fe5ffef20a7c30addf6320561e669</id>
<content type='text'>
This helper prints warning if direct I/O write failed to invalidate cache,
and set EIO at inode to warn usersapce about possible data corruption.

See also commit 5a9d929d6e13 ("iomap: report collisions between directio
and buffered writes to userspace").

Direct I/O is supported by non-disk filesystems, for example NFS.  Thus
generic code needs this even in kernel without CONFIG_BLOCK.

Link: http://lkml.kernel.org/r/157270038074.4812.7980855544557488880.stgit@buzz
Signed-off-by: Konstantin Khlebnikov &lt;khlebnikov@yandex-team.ru&gt;
Reviewed-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This helper prints warning if direct I/O write failed to invalidate cache,
and set EIO at inode to warn usersapce about possible data corruption.

See also commit 5a9d929d6e13 ("iomap: report collisions between directio
and buffered writes to userspace").

Direct I/O is supported by non-disk filesystems, for example NFS.  Thus
generic code needs this even in kernel without CONFIG_BLOCK.

Link: http://lkml.kernel.org/r/157270038074.4812.7980855544557488880.stgit@buzz
Signed-off-by: Konstantin Khlebnikov &lt;khlebnikov@yandex-team.ru&gt;
Reviewed-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "vfs: properly and reliably lock f_pos in fdget_pos()"</title>
<updated>2019-11-26T19:34:06+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-11-26T19:34:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2be7d348fe924f0c5583c6a805bd42cecda93104'/>
<id>2be7d348fe924f0c5583c6a805bd42cecda93104</id>
<content type='text'>
This reverts commit 0be0ee71816b2b6725e2b4f32ad6726c9d729777.

I was hoping it would be benign to switch over entirely to FMODE_STREAM,
and we'd have just a couple of small fixups we'd need, but it looks like
we're not quite there yet.

While it worked fine on both my desktop and laptop, they are fairly
similar in other respects, and run mostly the same loads.  Kenneth
Crudup reports that it seems to break both his vmware installation and
the KDE upower service.  In both cases apparently leading to timeouts
due to waitinmg for the f_pos lock.

There are a number of character devices in particular that definitely
want stream-like behavior, but that currently don't get marked as
streams, and as a result get the exclusion between concurrent
read()/write() on the same file descriptor.  Which doesn't work well for
them.

The most obvious example if this is /dev/console and /dev/tty, which use
console_fops and tty_fops respectively (and ptmx_fops for the pty master
side).  It may be that it's just this that causes problems, but we
clearly weren't ready yet.

Because there's a number of other likely common cases that don't have
llseek implementations and would seem to act as stream devices:

  /dev/fuse		(fuse_dev_operations)
  /dev/mcelog		(mce_chrdev_ops)
  /dev/mei0		(mei_fops)
  /dev/net/tun		(tun_fops)
  /dev/nvme0		(nvme_dev_fops)
  /dev/tpm0		(tpm_fops)
  /proc/self/ns/mnt	(ns_file_operations)
  /dev/snd/pcm*		(snd_pcm_f_ops[])

and while some of these could be trivially automatically detected by the
vfs layer when the character device is opened by just noticing that they
have no read or write operations either, it often isn't that obvious.

Some character devices most definitely do use the file position, even if
they don't allow seeking: the firmware update code, for example, uses
simple_read_from_buffer() that does use f_pos, but doesn't allow seeking
back and forth.

We'll revisit this when there's a better way to detect the problem and
fix it (possibly with a coccinelle script to do more of the FMODE_STREAM
annotations).

Reported-by: Kenneth R. Crudup &lt;kenny@panix.com&gt;
Cc: Kirill Smelkov &lt;kirr@nexedi.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit 0be0ee71816b2b6725e2b4f32ad6726c9d729777.

I was hoping it would be benign to switch over entirely to FMODE_STREAM,
and we'd have just a couple of small fixups we'd need, but it looks like
we're not quite there yet.

While it worked fine on both my desktop and laptop, they are fairly
similar in other respects, and run mostly the same loads.  Kenneth
Crudup reports that it seems to break both his vmware installation and
the KDE upower service.  In both cases apparently leading to timeouts
due to waitinmg for the f_pos lock.

There are a number of character devices in particular that definitely
want stream-like behavior, but that currently don't get marked as
streams, and as a result get the exclusion between concurrent
read()/write() on the same file descriptor.  Which doesn't work well for
them.

The most obvious example if this is /dev/console and /dev/tty, which use
console_fops and tty_fops respectively (and ptmx_fops for the pty master
side).  It may be that it's just this that causes problems, but we
clearly weren't ready yet.

Because there's a number of other likely common cases that don't have
llseek implementations and would seem to act as stream devices:

  /dev/fuse		(fuse_dev_operations)
  /dev/mcelog		(mce_chrdev_ops)
  /dev/mei0		(mei_fops)
  /dev/net/tun		(tun_fops)
  /dev/nvme0		(nvme_dev_fops)
  /dev/tpm0		(tpm_fops)
  /proc/self/ns/mnt	(ns_file_operations)
  /dev/snd/pcm*		(snd_pcm_f_ops[])

and while some of these could be trivially automatically detected by the
vfs layer when the character device is opened by just noticing that they
have no read or write operations either, it often isn't that obvious.

Some character devices most definitely do use the file position, even if
they don't allow seeking: the firmware update code, for example, uses
simple_read_from_buffer() that does use f_pos, but doesn't allow seeking
back and forth.

We'll revisit this when there's a better way to detect the problem and
fix it (possibly with a coccinelle script to do more of the FMODE_STREAM
annotations).

Reported-by: Kenneth R. Crudup &lt;kenny@panix.com&gt;
Cc: Kirill Smelkov &lt;kirr@nexedi.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for-5.5/disk-revalidate-20191122' of git://git.kernel.dk/linux-block</title>
<updated>2019-11-25T19:37:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-11-25T19:37:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7e5192b93c3b8661791f65f0d477d0da234ca202'/>
<id>7e5192b93c3b8661791f65f0d477d0da234ca202</id>
<content type='text'>
Pull disk revalidation updates from Jens Axboe:
 "This continues the work that Jan Kara started to thoroughly cleanup
  and consolidate how we handle rescans and revalidations"

* tag 'for-5.5/disk-revalidate-20191122' of git://git.kernel.dk/linux-block:
  block: move clearing bd_invalidated into check_disk_size_change
  block: remove (__)blkdev_reread_part as an exported API
  block: fix bdev_disk_changed for non-partitioned devices
  block: move rescan_partitions to fs/block_dev.c
  block: merge invalidate_partitions into rescan_partitions
  block: refactor rescan_partitions
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull disk revalidation updates from Jens Axboe:
 "This continues the work that Jan Kara started to thoroughly cleanup
  and consolidate how we handle rescans and revalidations"

* tag 'for-5.5/disk-revalidate-20191122' of git://git.kernel.dk/linux-block:
  block: move clearing bd_invalidated into check_disk_size_change
  block: remove (__)blkdev_reread_part as an exported API
  block: fix bdev_disk_changed for non-partitioned devices
  block: move rescan_partitions to fs/block_dev.c
  block: merge invalidate_partitions into rescan_partitions
  block: refactor rescan_partitions
</pre>
</div>
</content>
</entry>
<entry>
<title>vfs: properly and reliably lock f_pos in fdget_pos()</title>
<updated>2019-11-25T18:01:53+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-11-11T23:51:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0be0ee71816b2b6725e2b4f32ad6726c9d729777'/>
<id>0be0ee71816b2b6725e2b4f32ad6726c9d729777</id>
<content type='text'>
fdget_pos() is used by file operations that will read and update f_pos:
things like "read()", "write()" and "lseek()" (but not, for example,
"pread()/pwrite" that get their file positions elsewhere).

However, it had two separate escape clauses for this, because not
everybody wants or needs serialization of the file position.

The first and most obvious case is the "file descriptor doesn't have a
position at all", ie a stream-like file.  Except we didn't actually use
FMODE_STREAM, but instead used FMODE_ATOMIC_POS.  The reason for that
was that FMODE_STREAM didn't exist back in the days, but also that we
didn't want to mark all the special cases, so we only marked the ones
that _required_ position atomicity according to POSIX - regular files
and directories.

The case one was intentionally lazy, but now that we _do_ have
FMODE_STREAM we could and should just use it.  With the change to use
FMODE_STREAM, there are no remaining uses for FMODE_ATOMIC_POS, and all
the code to set it is deleted.

Any cases where we don't want the serialization because the driver (or
subsystem) doesn't use the file position should just be updated to do
"stream_open()".  We've done that for all the obvious and common
situations, we may need a few more.  Quoting Kirill Smelkov in the
original FMODE_STREAM thread (see link below for full email):

 "And I appreciate if people could help at least somehow with "getting
  rid of mixed case entirely" (i.e. always lock f_pos_lock on
  !FMODE_STREAM), because this transition starts to diverge from my
  particular use-case too far. To me it makes sense to do that
  transition as follows:

   - convert nonseekable_open -&gt; stream_open via stream_open.cocci;
   - audit other nonseekable_open calls and convert left users that
     truly don't depend on position to stream_open;
   - extend stream_open.cocci to analyze alloc_file_pseudo as well (this
     will cover pipes and sockets), or maybe convert pipes and sockets
     to FMODE_STREAM manually;
   - extend stream_open.cocci to analyze file_operations that use
     no_llseek or noop_llseek, but do not use nonseekable_open or
     alloc_file_pseudo. This might find files that have stream semantic
     but are opened differently;
   - extend stream_open.cocci to analyze file_operations whose
     .read/.write do not use ppos at all (independently of how file was
     opened);
   - ...
   - after that remove FMODE_ATOMIC_POS and always take f_pos_lock if
     !FMODE_STREAM;
   - gather bug reports for deadlocked read/write and convert missed
     cases to FMODE_STREAM, probably extending stream_open.cocci along
     the road to catch similar cases

  i.e. always take f_pos_lock unless a file is explicitly marked as
  being stream, and try to find and cover all files that are streams"

We have not done the "extend stream_open.cocci to analyze
alloc_file_pseudo" as well, but the previous commit did manually handle
the case of pipes and sockets.

The other case where we can avoid locking f_pos is the "this file
descriptor only has a single user and it is us, and thus there is no
need to lock it".

The second test was correct, although a bit subtle and worth just
re-iterating here.  There are two kinds of other sources of references
to the same file descriptor: file descriptors that have been explicitly
shared across fork() or with dup(), and file tables having elevated
reference counts due to threading (or explicit file sharing with
clone()).

The first case would have incremented the file count explicitly, and in
the second case the previous __fdget() would have incremented it for us
and set the FDPUT_FPUT flag.

But in both cases the file count would be greater than one, so the
"file_count(file) &gt; 1" test catches both situations.  Also note that if
file_count is 1, that also means that no other thread can have access to
the file table, so there also cannot be races with concurrent calls to
dup()/fork()/clone() that would increment the file count any other way.

Link: https://lore.kernel.org/linux-fsdevel/20190413184404.GA13490@deco.navytux.spb.ru
Cc: Kirill Smelkov &lt;kirr@nexedi.com&gt;
Cc: Eic Dumazet &lt;edumazet@google.com&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Cc: Marco Elver &lt;elver@google.com&gt;
Cc: Andrea Parri &lt;parri.andrea@gmail.com&gt;
Cc: Paul McKenney &lt;paulmck@kernel.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
fdget_pos() is used by file operations that will read and update f_pos:
things like "read()", "write()" and "lseek()" (but not, for example,
"pread()/pwrite" that get their file positions elsewhere).

However, it had two separate escape clauses for this, because not
everybody wants or needs serialization of the file position.

The first and most obvious case is the "file descriptor doesn't have a
position at all", ie a stream-like file.  Except we didn't actually use
FMODE_STREAM, but instead used FMODE_ATOMIC_POS.  The reason for that
was that FMODE_STREAM didn't exist back in the days, but also that we
didn't want to mark all the special cases, so we only marked the ones
that _required_ position atomicity according to POSIX - regular files
and directories.

The case one was intentionally lazy, but now that we _do_ have
FMODE_STREAM we could and should just use it.  With the change to use
FMODE_STREAM, there are no remaining uses for FMODE_ATOMIC_POS, and all
the code to set it is deleted.

Any cases where we don't want the serialization because the driver (or
subsystem) doesn't use the file position should just be updated to do
"stream_open()".  We've done that for all the obvious and common
situations, we may need a few more.  Quoting Kirill Smelkov in the
original FMODE_STREAM thread (see link below for full email):

 "And I appreciate if people could help at least somehow with "getting
  rid of mixed case entirely" (i.e. always lock f_pos_lock on
  !FMODE_STREAM), because this transition starts to diverge from my
  particular use-case too far. To me it makes sense to do that
  transition as follows:

   - convert nonseekable_open -&gt; stream_open via stream_open.cocci;
   - audit other nonseekable_open calls and convert left users that
     truly don't depend on position to stream_open;
   - extend stream_open.cocci to analyze alloc_file_pseudo as well (this
     will cover pipes and sockets), or maybe convert pipes and sockets
     to FMODE_STREAM manually;
   - extend stream_open.cocci to analyze file_operations that use
     no_llseek or noop_llseek, but do not use nonseekable_open or
     alloc_file_pseudo. This might find files that have stream semantic
     but are opened differently;
   - extend stream_open.cocci to analyze file_operations whose
     .read/.write do not use ppos at all (independently of how file was
     opened);
   - ...
   - after that remove FMODE_ATOMIC_POS and always take f_pos_lock if
     !FMODE_STREAM;
   - gather bug reports for deadlocked read/write and convert missed
     cases to FMODE_STREAM, probably extending stream_open.cocci along
     the road to catch similar cases

  i.e. always take f_pos_lock unless a file is explicitly marked as
  being stream, and try to find and cover all files that are streams"

We have not done the "extend stream_open.cocci to analyze
alloc_file_pseudo" as well, but the previous commit did manually handle
the case of pipes and sockets.

The other case where we can avoid locking f_pos is the "this file
descriptor only has a single user and it is us, and thus there is no
need to lock it".

The second test was correct, although a bit subtle and worth just
re-iterating here.  There are two kinds of other sources of references
to the same file descriptor: file descriptors that have been explicitly
shared across fork() or with dup(), and file tables having elevated
reference counts due to threading (or explicit file sharing with
clone()).

The first case would have incremented the file count explicitly, and in
the second case the previous __fdget() would have incremented it for us
and set the FDPUT_FPUT flag.

But in both cases the file count would be greater than one, so the
"file_count(file) &gt; 1" test catches both situations.  Also note that if
file_count is 1, that also means that no other thread can have access to
the file table, so there also cannot be races with concurrent calls to
dup()/fork()/clone() that would increment the file count any other way.

Link: https://lore.kernel.org/linux-fsdevel/20190413184404.GA13490@deco.navytux.spb.ru
Cc: Kirill Smelkov &lt;kirr@nexedi.com&gt;
Cc: Eic Dumazet &lt;edumazet@google.com&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Cc: Marco Elver &lt;elver@google.com&gt;
Cc: Andrea Parri &lt;parri.andrea@gmail.com&gt;
Cc: Paul McKenney &lt;paulmck@kernel.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: remove (__)blkdev_reread_part as an exported API</title>
<updated>2019-11-14T14:43:59+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2019-11-14T14:34:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f0b870df80bc70dad432fd0c142bb709a49964f5'/>
<id>f0b870df80bc70dad432fd0c142bb709a49964f5</id>
<content type='text'>
In general drivers should never mess with partition tables directly.
Unfortunately s390 and loop do for somewhat historic reasons, but they
can use bdev_disk_changed directly instead when we export it as they
satisfy the sanity checks we have in __blkdev_reread_part.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Stefan Haberland &lt;sth@linux.ibm.com&gt;	[dasd]
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In general drivers should never mess with partition tables directly.
Unfortunately s390 and loop do for somewhat historic reasons, but they
can use bdev_disk_changed directly instead when we export it as they
satisfy the sanity checks we have in __blkdev_reread_part.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Stefan Haberland &lt;sth@linux.ibm.com&gt;	[dasd]
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: move rescan_partitions to fs/block_dev.c</title>
<updated>2019-11-14T14:43:21+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2019-11-14T14:34:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a1548b674403c0de70cc29a1575689917ba60157'/>
<id>a1548b674403c0de70cc29a1575689917ba60157</id>
<content type='text'>
Large parts of rescan_partitions aren't about partitions, and
moving it to block_dev.c will allow for some further cleanups by
merging it into its only caller.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Large parts of rescan_partitions aren't about partitions, and
moving it to block_dev.c will allow for some further cleanups by
merging it into its only caller.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fs: add generic UNRESVSP and ZERO_RANGE ioctl handlers</title>
<updated>2019-10-28T15:37:55+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2019-10-25T05:26:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=837a6e7f5cdb5e411c6187729e12962c2705160d'/>
<id>837a6e7f5cdb5e411c6187729e12962c2705160d</id>
<content type='text'>
These use the same scheme as the pre-existing mapping of the XFS
RESVP ioctls to -&gt;falloc, so just extend it and remove the XFS
implementation.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
[darrick: fix compile error on s390]
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
These use the same scheme as the pre-existing mapping of the XFS
RESVP ioctls to -&gt;falloc, so just extend it and remove the XFS
implementation.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
[darrick: fix compile error on s390]
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
