linux-stable.git/include/linux/shmem_fs.h, branch v6.6.2

tmpfs: track free_ispace instead of free_inodes

2023-08-09T07:15:51+00:00

In preparation for assigning some inode space to extended attributes,
keep track of free_ispace instead of number of free_inodes: as if one
tmpfs inode (and accompanying dentry) occupies very approximately 1KiB.

Unsigned long is large enough for free_ispace, on 64-bit and on 32-bit:
but take care to enforce the maximum.  And fix the nr_blocks maximum on
32-bit: S64_MAX would be too big for it there, so say LONG_MAX instead.

Delete the incorrect limited<->unlimited blocks/inodes comment above
shmem_reconfigure(): leave it to the error messages below to describe.

Signed-off-by: Hugh Dickins 
Reviewed-by: Jan Kara 
Reviewed-by: Carlos Maiolino 
Message-Id: <4fe1739-d9e7-8dfd-5bce-12e7339711da@google.com>
Signed-off-by: Christian Brauner

shmem: stable directory offsets

2023-08-09T07:15:40+00:00

The current cursor-based directory offset mechanism doesn't work
when a tmpfs filesystem is exported via NFS. This is because NFS
clients do not open directories. Each server-side READDIR operation
has to open the directory, read it, then close it. The cursor state
for that directory, being associated strictly with the opened
struct file, is thus discarded after each NFS READDIR operation.

Directory offsets are cached not only by NFS clients, but also by
user space libraries on those clients. Essentially there is no way
to invalidate those caches when directory offsets have changed on
an NFS server after the offset-to-dentry mapping changes. Thus the
whole application stack depends on unchanging directory offsets.

The solution we've come up with is to make the directory offset for
each file in a tmpfs filesystem stable for the life of the directory
entry it represents.

shmem_readdir() and shmem_dir_llseek() now use an xarray to map each
directory offset (an loff_t integer) to the memory address of a
struct dentry.

Signed-off-by: Chuck Lever 
Message-Id: <168814734331.530310.3911190551060453102.stgit@manet.1015granger.net>
Signed-off-by: Christian Brauner

shmem: Add default quota limit mount options

2023-08-09T07:15:40+00:00

Allow system administrator to set default global quota limits at tmpfs
mount time.

Signed-off-by: Lukas Czerner 
Signed-off-by: Carlos Maiolino 
Reviewed-by: Jan Kara 
Message-Id: <20230725144510.253763-7-cem@kernel.org>
Signed-off-by: Christian Brauner

shmem: quota support

2023-08-09T07:15:39+00:00

Now the basic infra-structure is in place, enable quota support for tmpfs.

This offers user and group quotas to tmpfs (project quotas will be added
later). Also, as other filesystems, the tmpfs quota is not supported
within user namespaces yet, so idmapping is not translated.

Signed-off-by: Lukas Czerner 
Signed-off-by: Carlos Maiolino 
Reviewed-by: Jan Kara 
Message-Id: <20230725144510.253763-6-cem@kernel.org>
Signed-off-by: Christian Brauner

shmem: prepare shmem quota infrastructure

2023-08-09T07:15:39+00:00

Add new shmem quota format, its quota_format_ops together with
dquot_operations

Signed-off-by: Lukas Czerner 
Signed-off-by: Carlos Maiolino 
Reviewed-by: Jan Kara 
Message-Id: <20230725144510.253763-5-cem@kernel.org>
Signed-off-by: Christian Brauner

userfaultfd: convert mfill_atomic() to use a folio

2023-04-18T23:29:55+00:00

Convert mfill_atomic_pte_copy(), shmem_mfill_atomic_pte() and
mfill_atomic_pte() to take in a folio pointer.

Convert mfill_atomic() to use a folio.  Convert page_kaddr to kaddr in
mfill_atomic().

Link: https://lkml.kernel.org/r/20230410133932.32288-7-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng 
Reviewed-by: Mike Kravetz 
Cc: Kefeng Wang 
Cc: Matthew Wilcox 
Cc: Muchun Song 
Cc: Nanyong Sun 
Cc: Sidhartha Kumar 
Cc: Vishal Moola (Oracle) 
Signed-off-by: Andrew Morton

smaps: fix defined but not used smaps_shmem_walk_ops

2023-04-18T23:29:54+00:00

When !CONFIG_SHMEM smaps_shmem_walk_ops is defined but not used,
triggering a compiler warning.  To avoid the warning remove the #ifdef
around the usage.  This has no effect because shmem_mapping() is a stub
returning false when !CONFIG_SHMEM so the code will be compiled out,
however we now need to also provide a stub for shmem_swap_usage().

Link: https://lkml.kernel.org/r/20230405103819.151246-1-steven.price@arm.com
Fixes: 7b86ac3371b7 ("pagewalk: separate function pointers from iterator data")
Signed-off-by: Steven Price 
Reported-by: kernel test robot 
  Link: https://lore.kernel.org/oe-kbuild-all/202304031749.UiyJpxzF-lkp@intel.com/
Reviewed-by: Jason Gunthorpe 
Cc: Christoph Hellwig 
Cc: Alexey Dobriyan 
Cc: Thomas Hellström 
Signed-off-by: Andrew Morton

mm: userfaultfd: combine 'mode' and 'wp_copy' arguments

2023-04-06T02:42:48+00:00

Many userfaultfd ioctl functions take both a 'mode' and a 'wp_copy'
argument.  In future commits we plan to plumb the flags through to more
places, so we'd be proliferating the very long argument list even further.

Let's take the time to simplify the argument list.  Combine the two
arguments into one - and generalize, so when we add more flags in the
future, it doesn't imply more function arguments.

Since the modes (copy, zeropage, continue) are mutually exclusive, store
them as an integer value (0, 1, 2) in the low bits.  Place combine-able
flag bits in the high bits.

This is quite similar to an earlier patch proposed by Nadav Amit
("userfaultfd: introduce uffd_flags" [1]).  The main difference is that
patch only handled flags, whereas this patch *also* combines the "mode"
argument into the same type to shorten the argument list.

[1]: https://lore.kernel.org/all/20220619233449.181323-2-namit@vmware.com/

Link: https://lkml.kernel.org/r/20230314221250.682452-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: James Houghton 
Acked-by: Peter Xu 
Acked-by: Mike Rapoport (IBM) 
Cc: Al Viro 
Cc: Hugh Dickins 
Cc: Jan Kara 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm: userfaultfd: don't pass around both mm and vma

2023-04-06T02:42:47+00:00

Quite a few userfaultfd functions took both mm and vma pointers as
arguments.  Since the mm is trivially accessible via vma->vm_mm, there's
no reason to pass both; it just needlessly extends the already long
argument list.

Get rid of the mm pointer, where possible, to shorten the argument list.

Link: https://lkml.kernel.org/r/20230314221250.682452-3-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: Peter Xu 
Acked-by: Mike Rapoport (IBM) 
Cc: Al Viro 
Cc: Hugh Dickins 
Cc: James Houghton 
Cc: Jan Kara 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Nadav Amit 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

shmem: add support to ignore swap

2023-03-28T23:20:15+00:00

In doing experimentations with shmem having the option to avoid swap
becomes a useful mechanism.  One of the *raves* about brd over shmem is
you can avoid swap, but that's not really a good reason to use brd if we
can instead use shmem.  Using brd has its own good reasons to exist, but
just because "tmpfs" doesn't let you do that is not a great reason to
avoid it if we can easily add support for it.

I don't add support for reconfiguring incompatible options, but if we
really wanted to we can add support for that.

To avoid swap we use mapping_set_unevictable() upon inode creation, and
put a WARN_ON_ONCE() stop-gap on writepages() for reclaim.

Link: https://lkml.kernel.org/r/20230309230545.2930737-7-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Acked-by: Christian Brauner 
Tested-by: Xin Hao 
Reviewed-by: Davidlohr Bueso 
Cc: Adam Manzanares 
Cc: David Hildenbrand 
Cc: Davidlohr Bueso 
Cc: Hugh Dickins 
Cc: Kees Cook 
Cc: Matthew Wilcox 
Cc: Pankaj Raghav 
Cc: Yosry Ahmed 
Signed-off-by: Andrew Morton