lib/string.c: introduce memchr_inv()

memchr_inv() is mainly used to check whether the whole buffer is filled
with just a specified byte.

The function name and prototype are stolen from logfs and the
implementation is from SLUB.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: Joern Engel <joern@logfs.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 0 insertions, 23 deletions

diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index f22d108bfa5d..398ecff6e548 100644
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -618,7 +618,6 @@ static inline int logfs_buf_recover(struct logfs_area *area, u64 ofs,
 struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index);
 void emergency_read_end(struct page *page);
 void logfs_crash_dump(struct super_block *sb);
-void *memchr_inv(const void *s, int c, size_t n);
 int logfs_statfs(struct dentry *dentry, struct kstatfs *stats);
 int logfs_check_ds(struct logfs_disk_super *ds);
 int logfs_write_sb(struct super_block *sb);
diff --git a/fs/logfs/super.c b/fs/logfs/super.c
index ce03a182c771..f2697e4df109 100644
--- a/fs/logfs/super.c
+++ b/fs/logfs/super.c
@@ -91,28 +91,6 @@ void logfs_crash_dump(struct super_block *sb)
 }
 
 /*
- * TODO: move to lib/string.c
- */
-/**
- * memchr_inv - Find a character in an area of memory.
- * @s: The memory area
- * @c: The byte to search for
- * @n: The size of the area.
- *
- * returns the address of the first character other than @c, or %NULL
- * if the whole buffer contains just @c.
- */
-void *memchr_inv(const void *s, int c, size_t n)
-{
-        const unsigned char *p = s;
-        while (n-- != 0)
-                if ((unsigned char)c != *p++)
-                        return (void *)(p - 1);
-
-        return NULL;
-}
-
-/*
  * FIXME: There should be a reserve for root, similar to ext2.
  */
 int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)