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ocfs2: Use zero-sized array and struct_size() in kzalloc()

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Update the code to use a zero-sized array instead of a pointer in
structure ocfs2_slot_info and use struct_size() in kzalloc().

Notice that one of the more common cases of allocation size calculations
is finding the size of a structure that has a zero-sized array at the
end, along with memory for some number of elements for that array.  For
example:

  struct foo {
      int stuff;
      void *entry[];
  };

  instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

  instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Link: http://lkml.kernel.org/r/20190108191903.GA22056@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Gustavo A. R. Silva 2019-03-05 15:41:48 -08:00 committed by Linus Torvalds
parent 5500ab4ed3
commit f402cf03fc
1 changed files with 2 additions and 6 deletions
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8
fs/ocfs2/slot_map.c
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@ -55,7 +55,7 @@ struct ocfs2_slot_info {
unsigned int si_blocks;
struct buffer_head **si_bh;
unsigned int si_num_slots;
struct ocfs2_slot *si_slots;
struct ocfs2_slot si_slots[];
};
@ -420,9 +420,7 @@ int ocfs2_init_slot_info(struct ocfs2_super *osb)
struct inode *inode = NULL;
struct ocfs2_slot_info *si;
si = kzalloc(sizeof(struct ocfs2_slot_info) +
(sizeof(struct ocfs2_slot) * osb->max_slots),
GFP_KERNEL);
si = kzalloc(struct_size(si, si_slots, osb->max_slots), GFP_KERNEL);
if (!si) {
status = -ENOMEM;
mlog_errno(status);
@ -431,8 +429,6 @@ int ocfs2_init_slot_info(struct ocfs2_super *osb)
si->si_extended = ocfs2_uses_extended_slot_map(osb);
si->si_num_slots = osb->max_slots;
si->si_slots = (struct ocfs2_slot *)((char *)si +
sizeof(struct ocfs2_slot_info));
inode = ocfs2_get_system_file_inode(osb, SLOT_MAP_SYSTEM_INODE,
OCFS2_INVALID_SLOT);