Pass a struct btrfs_inode to btrfs_fill_inode() as it's an internal
interface, allowing to remove some use of BTRFS_I.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

On x86_64 and a release kernel, there's a 4 bytes hole in the structure
after the ref count field:

  struct btrfs_delayed_node {
          u64                        inode_id;             /*     0     8 */
          u64                        bytes_reserved;       /*     8     8 */
          struct btrfs_root *        root;                 /*    16     8 */
          struct list_head           n_list;               /*    24    16 */
          struct list_head           p_list;               /*    40    16 */
          struct rb_root_cached      ins_root;             /*    56    16 */
          /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */
          struct rb_root_cached      del_root;             /*    72    16 */
          struct mutex               mutex;                /*    88    32 */
          struct btrfs_inode_item    inode_item;           /*   120   160 */
          /* --- cacheline 4 boundary (256 bytes) was 24 bytes ago --- */
          refcount_t                 refs;                 /*   280     4 */

          /* XXX 4 bytes hole, try to pack */

          u64                        index_cnt;            /*   288     8 */
          long unsigned int          flags;                /*   296     8 */
          int                        count;                /*   304     4 */
          u32                        curr_index_batch_size; /*   308     4 */
          u32                        index_item_leaves;    /*   312     4 */

          /* size: 320, cachelines: 5, members: 15 */
          /* sum members: 312, holes: 1, sum holes: 4 */
          /* padding: 4 */
  };

Move the 'count' field, which is 4 bytes long, to just below the ref count
field, so we eliminate the hole and reduce the structure size from 320
bytes down to 312 bytes:

  struct btrfs_delayed_node {
          u64                        inode_id;             /*     0     8 */
          u64                        bytes_reserved;       /*     8     8 */
          struct btrfs_root *        root;                 /*    16     8 */
          struct list_head           n_list;               /*    24    16 */
          struct list_head           p_list;               /*    40    16 */
          struct rb_root_cached      ins_root;             /*    56    16 */
          /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */
          struct rb_root_cached      del_root;             /*    72    16 */
          struct mutex               mutex;                /*    88    32 */
          struct btrfs_inode_item    inode_item;           /*   120   160 */
          /* --- cacheline 4 boundary (256 bytes) was 24 bytes ago --- */
          refcount_t                 refs;                 /*   280     4 */
          int                        count;                /*   284     4 */
          u64                        index_cnt;            /*   288     8 */
          long unsigned int          flags;                /*   296     8 */
          u32                        curr_index_batch_size; /*   304     4 */
          u32                        index_item_leaves;    /*   308     4 */

          /* size: 312, cachelines: 5, members: 15 */
          /* last cacheline: 56 bytes */
  };

This now allows to have 13 delayed nodes per 4K page instead of 12.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Pass a struct btrfs_inode to btrfs_readdir_get_delayed_items() as it's
an internal interface, allowing to remove some use of BTRFS_I.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

Pass a struct btrfs_inode to btrfs_readdir_put_delayed_items() as it's
an internal interface, allowing to remove some use of BTRFS_I.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

We can add const to many parameters, this is for clarity and minor
addition to safety. There are some minor effects, in the assembly
code and .ko measured on release config. This patch does not cover all
possible conversions.

Signed-off-by: David Sterba <dsterba@suse.com>

This is a simple initializer and not on any hot path, it does not need
to be static inline.

Signed-off-by: David Sterba <dsterba@suse.com>

Do a cleanup in more headers:

- add forward declarations for types referenced by pointers
- add includes when types need them

This fixes potential compilation problems if the headers are reordered
or the missing includes are not provided indirectly.

Signed-off-by: David Sterba <dsterba@suse.com>

The root argument for btrfs_delayed_update_inode() always matches the root
of the given inode, so remove the root argument and get it from the inode
argument.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

While there, use struct_size() helper, instead of the open-coded
version, to calculate the size for the allocation of the whole
flexible structure, including of course, the flexible-array member.

This code was found with the help of Coccinelle, and audited and
fixed manually.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

The readdir implementation currently processes always up to the last index
it finds. This however can result in an infinite loop if the directory has
a large number of entries such that they won't all fit in the given buffer
passed to the readdir callback, that is, dir_emit() returns a non-zero
value. Because in that case readdir() will be called again and if in the
meanwhile new directory entries were added and we still can't put all the
remaining entries in the buffer, we keep repeating this over and over.

The following C program and test script reproduce the problem:

  $ cat /mnt/readdir_prog.c
  #include <sys/types.h>
  #include <dirent.h>
  #include <stdio.h>

  int main(int argc, char *argv[])
  {
    DIR *dir = opendir(".");
    struct dirent *dd;

    while ((dd = readdir(dir))) {
      printf("%s\n", dd->d_name);
      rename(dd->d_name, "TEMPFILE");
      rename("TEMPFILE", dd->d_name);
    }
    closedir(dir);
  }

  $ gcc -o /mnt/readdir_prog /mnt/readdir_prog.c

  $ cat test.sh
  #!/bin/bash

  DEV=/dev/sdi
  MNT=/mnt/sdi

  mkfs.btrfs -f $DEV &> /dev/null
  #mkfs.xfs -f $DEV &> /dev/null
  #mkfs.ext4 -F $DEV &> /dev/null

  mount $DEV $MNT

  mkdir $MNT/testdir
  for ((i = 1; i <= 2000; i++)); do
      echo -n > $MNT/testdir/file_$i
  done

  cd $MNT/testdir
  /mnt/readdir_prog

  cd /mnt

  umount $MNT

This behaviour is surprising to applications and it's unlike ext4, xfs,
tmpfs, vfat and other filesystems, which always finish. In this case where
new entries were added due to renames, some file names may be reported
more than once, but this varies according to each filesystem - for example
ext4 never reported the same file more than once while xfs reports the
first 13 file names twice.

So change our readdir implementation to track the last index number when
opendir() is called and then make readdir() never process beyond that
index number. This gives the same behaviour as ext4.

Reported-by: Rob Landley <rob@landley.net>
Link: https://lore.kernel.org/linux-btrfs/2c8c55ec-04c6-e0dc-9c5c-8c7924778c35@landley.net/
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217681
CC: stable@vger.kernel.org # 6.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>