ocfs2: use flexible array in 'struct ocfs2_recovery_map'

Turn 'rm_entries' in 'struct ocfs2_recovery_map' into a flexible array.

The advantages are:
   - save the size of a pointer when the new undo structure is allocated
   - avoid some always ugly pointer arithmetic to get the address of
    'rm_entries'
   - avoid an indirection when the array is accessed

While at it, use struct_size() to compute the size of the new undo
structure.

Link: https://lkml.kernel.org/r/c645911ffd2720fce5e344c17de642518cd0db52.1689533270.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 25d8072..2f7e701 100644 (file)
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -178,16 +178,13 @@ int ocfs2_recovery_init(struct ocfs2_super *osb)
        osb->recovery_thread_task = NULL;
        init_waitqueue_head(&osb->recovery_event);
 
-       rm = kzalloc(sizeof(struct ocfs2_recovery_map) +
-                    osb->max_slots * sizeof(unsigned int),
+       rm = kzalloc(struct_size(rm, rm_entries, osb->max_slots),
                     GFP_KERNEL);
        if (!rm) {
                mlog_errno(-ENOMEM);
                return -ENOMEM;
        }
 
-       rm->rm_entries = (unsigned int *)((char *)rm +
-                                         sizeof(struct ocfs2_recovery_map));
        osb->recovery_map = rm;
 
        return 0;

diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 41c382f..41c9fe7 100644 (file)
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -29,7 +29,7 @@ struct ocfs2_dinode;
 
 struct ocfs2_recovery_map {
        unsigned int rm_used;
-       unsigned int *rm_entries;
+       unsigned int rm_entries[];
 };