linux.git/fs/zonefs, branch v6.3

zonefs: Do not propagate iomap_dio_rw() ENOTBLK error to user space

2023-03-30T11:56:02+00:00

The call to invalidate_inode_pages2_range() in __iomap_dio_rw() may
fail, in which case -ENOTBLK is returned and this error code is
propagated back to user space trhough iomap_dio_rw() ->
zonefs_file_dio_write() return chain. This error code is fairly obscure
and may confuse the user. Avoid this and be consistent with the behavior
of zonefs_file_dio_append() for similar invalidate_inode_pages2_range()
errors by returning -EBUSY to user space when iomap_dio_rw() returns
-ENOTBLK.

Suggested-by: Christoph Hellwig 
Fixes: 8dcc1a9d90c1 ("fs: New zonefs file system")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Tested-by: Hans Holmberg

zonefs: Always invalidate last cached page on append write

2023-03-30T11:55:49+00:00

When a direct append write is executed, the append offset may correspond
to the last page of a sequential file inode which might have been cached
already by buffered reads, page faults with mmap-read or non-direct
readahead. To ensure that the on-disk and cached data is consistant for
such last cached page, make sure to always invalidate it in
zonefs_file_dio_append(). If the invalidation fails, return -EBUSY to
userspace to differentiate from IO errors.

This invalidation will always be a no-op when the FS block size (device
zone write granularity) is equal to the page size (e.g. 4K).

Reported-by: Hans Holmberg 
Fixes: 02ef12a663c7 ("zonefs: use REQ_OP_ZONE_APPEND for sync DIO")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Tested-by: Hans Holmberg

zonefs: Fix error message in zonefs_file_dio_append()

2023-03-20T21:36:43+00:00

Since the expected write location in a sequential file is always at the
end of the file (append write), when an invalid write append location is
detected in zonefs_file_dio_append(), print the invalid written location
instead of the expected write location.

Fixes: a608da3bd730 ("zonefs: Detect append writes at invalid locations")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Reviewed-by: Himanshu Madhani

zonefs: Prevent uninitialized symbol 'size' warning

2023-03-20T21:36:34+00:00

In zonefs_file_dio_append(), initialize the variable size to 0 to
prevent compilation and static code analizers warning such as:

New smatch warnings:
fs/zonefs/file.c:441 zonefs_file_dio_append() error: uninitialized
symbol 'size'.

The warning is a false positive as size is never actually used
uninitialized.

No functional change.

Reported-by: kernel test robot 
Reported-by: Dan Carpenter 
Link: https://lore.kernel.org/r/202303191227.GL8Dprbi-lkp@intel.com/
Signed-off-by: Damien Le Moal 
Reviewed-by: Johannes Thumshirn 
Reviewed-by: Himanshu Madhani

Merge tag 'zonefs-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs

2023-02-22T22:11:54+00:00

Pull zonefs updates from Damien Le Moal:

 - Reorganize zonefs code to split file related operations to a new
   fs/zonefs/file.c file (me)

 - Modify zonefs to use dynamically allocated inodes and dentries (using
   the inode and dentry caches) instead of statically allocating
   everything on mount. This saves a significant amount of memory for
   very large zoned block devices with 10s of thousands of zones (me)

 - Make zonefs_sb_ktype a const struct kobj_type (Thomas)

* tag 'zonefs-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs:
  zonefs: make kobj_type structure constant
  zonefs: Cache zone group directory inodes
  zonefs: Dynamically create file inodes when needed
  zonefs: Separate zone information from inode information
  zonefs: Reduce struct zonefs_inode_info size
  zonefs: Simplify IO error handling
  zonefs: Reorganize code

Merge tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

2023-02-20T19:53:11+00:00

Pull vfs idmapping updates from Christian Brauner:

 - Last cycle we introduced the dedicated struct mnt_idmap type for
   mount idmapping and the required infrastucture in 256c8aed2b42 ("fs:
   introduce dedicated idmap type for mounts"). As promised in last
   cycle's pull request message this converts everything to rely on
   struct mnt_idmap.

   Currently we still pass around the plain namespace that was attached
   to a mount. This is in general pretty convenient but it makes it easy
   to conflate namespaces that are relevant on the filesystem with
   namespaces that are relevant on the mount level. Especially for
   non-vfs developers without detailed knowledge in this area this was a
   potential source for bugs.

   This finishes the conversion. Instead of passing the plain namespace
   around this updates all places that currently take a pointer to a
   mnt_userns with a pointer to struct mnt_idmap.

   Now that the conversion is done all helpers down to the really
   low-level helpers only accept a struct mnt_idmap argument instead of
   two namespace arguments.

   Conflating mount and other idmappings will now cause the compiler to
   complain loudly thus eliminating the possibility of any bugs. This
   makes it impossible for filesystem developers to mix up mount and
   filesystem idmappings as they are two distinct types and require
   distinct helpers that cannot be used interchangeably.

   Everything associated with struct mnt_idmap is moved into a single
   separate file. With that change no code can poke around in struct
   mnt_idmap. It can only be interacted with through dedicated helpers.
   That means all filesystems are and all of the vfs is completely
   oblivious to the actual implementation of idmappings.

   We are now also able to extend struct mnt_idmap as we see fit. For
   example, we can decouple it completely from namespaces for users that
   don't require or don't want to use them at all. We can also extend
   the concept of idmappings so we can cover filesystem specific
   requirements.

   In combination with the vfs{g,u}id_t work we finished in v6.2 this
   makes this feature substantially more robust and thus difficult to
   implement wrong by a given filesystem and also protects the vfs.

 - Enable idmapped mounts for tmpfs and fulfill a longstanding request.

   A long-standing request from users had been to make it possible to
   create idmapped mounts for tmpfs. For example, to share the host's
   tmpfs mount between multiple sandboxes. This is a prerequisite for
   some advanced Kubernetes cases. Systemd also has a range of use-cases
   to increase service isolation. And there are more users of this.

   However, with all of the other work going on this was way down on the
   priority list but luckily someone other than ourselves picked this
   up.

   As usual the patch is tiny as all the infrastructure work had been
   done multiple kernel releases ago. In addition to all the tests that
   we already have I requested that Rodrigo add a dedicated tmpfs
   testsuite for idmapped mounts to xfstests. It is to be included into
   xfstests during the v6.3 development cycle. This should add a slew of
   additional tests.

* tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping: (26 commits)
  shmem: support idmapped mounts for tmpfs
  fs: move mnt_idmap
  fs: port vfs{g,u}id helpers to mnt_idmap
  fs: port fs{g,u}id helpers to mnt_idmap
  fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap
  fs: port i_{g,u}id_{needs_}update() to mnt_idmap
  quota: port to mnt_idmap
  fs: port privilege checking helpers to mnt_idmap
  fs: port inode_owner_or_capable() to mnt_idmap
  fs: port inode_init_owner() to mnt_idmap
  fs: port acl to mnt_idmap
  fs: port xattr to mnt_idmap
  fs: port ->permission() to pass mnt_idmap
  fs: port ->fileattr_set() to pass mnt_idmap
  fs: port ->set_acl() to pass mnt_idmap
  fs: port ->get_acl() to pass mnt_idmap
  fs: port ->tmpfile() to pass mnt_idmap
  fs: port ->rename() to pass mnt_idmap
  fs: port ->mknod() to pass mnt_idmap
  fs: port ->mkdir() to pass mnt_idmap
  ...

zonefs: make kobj_type structure constant

2023-02-12T23:03:48+00:00

Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definition to prevent
modification at runtime.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Johannes Thumshirn 
Signed-off-by: Damien Le Moal

zonefs: Cache zone group directory inodes

2023-01-23T00:25:51+00:00

Since looking up any zone file inode requires looking up first the inode
for the directory representing the zone group of the file, ensuring that
the zone group inodes are always cached is desired. To do so, take an
extra reference on the zone groups directory inodes on mount, thus
avoiding the eviction of these inodes from the inode cache until the
volume is unmounted.

Signed-off-by: Damien Le Moal 
Reviewed-by: Johannes Thumshirn

zonefs: Dynamically create file inodes when needed

2023-01-23T00:25:51+00:00

Allocating and initializing all inodes and dentries for all files
results in a very large memory usage with high capacity zoned block
devices. For instance, with a 26 TB SMR HDD with over 96000 zones,
mounting the disk with zonefs results in about 130 MB of memory used,
the vast majority of this space being used for vfs inodes and dentries.

However, since a user will rarely access all zones at the same time,
dynamically creating file inodes and dentries on demand, similarly to
regular file systems, can significantly reduce memory usage.

This patch modifies mount processing to not create the inodes and
dentries for zone files. Instead, the directory inode operation
zonefs_lookup() and directory file operation zonefs_readdir() are
introduced to allocate and initialize inodes on-demand using the helper
functions zonefs_get_dir_inode() and zonefs_get_zgroup_inode().

Implementation of these functions is simple, relying on the static
nature of zonefs directories and files. Directory inodes are linked to
the volume zone groups (struct zonefs_zone_group) they represent by
using the directory inode i_private field. This simplifies the
implementation of the lookup and readdir operations.

Unreferenced zone file inodes can be evicted from the inode cache at any
time. In such case, the only inode information that cannot be recreated
from the zone information that is saved in the zone group data
structures attached to the volume super block is the inode uid, gid and
access rights. These values may have been changed by the user. To keep
these attributes for the life time of the mount, as before, the inode
mode, uid and gid are saved in the inode zone information and the saved
values are used to initialize regular file inodes when an inode lookup
happens. The zone information mode, uid and gid are initialized in
zonefs_init_zgroup() using the default values.

With these changes, the static minimal memory usage of a zonefs volume
is mostly reduced to the array of zone information for each zone group.
For the 26 TB SMR hard-disk mentioned above, the memory usage after
mount becomes about 5.4 MB, a reduction by a factor of 24 from the
initial 130 MB memory use.

Co-developed-by: Jorgen Hansen 
Signed-off-by: Damien Le Moal 
Reviewed-by: Johannes Thumshirn

zonefs: Separate zone information from inode information

2023-01-23T00:25:51+00:00

In preparation for adding dynamic inode allocation, separate an inode
zone information from the zonefs inode structure. The new data structure
zonefs_zone is introduced to store in memory information about a zone
that must be kept throughout the lifetime of the device mount.

Linking between a zone file inode and its zone information is done by
setting the inode i_private field to point to a struct zonefs_zone.
Using the i_private pointer avoids the need for adding a pointer in
struct zonefs_inode_info. Beside the vfs inode, this structure is
reduced to a mutex and a write open counter.

One struct zonefs_zone is created per file inode on mount. These
structures are organized in an array using the new struct
zonefs_zone_group data structure to represent zone groups. The
zonefs_zone arrays are indexed per file number (the index of a struct
zonefs_zone in its array directly gives the file number/name for that
zone file inode).

Signed-off-by: Damien Le Moal 
Reviewed-by: Johannes Thumshirn