| Message ID | 1596894336-49052-1-git-send-email-xianting_tian@126.com |
|---|---|
| State | Rejected |
| Headers | show |
| Series | ext4: use kmemdup_nul() instead of kstrndup() | expand |
On Sat 08-08-20 09:45:36, Xianting Tian wrote: > kmemdup_nul() is more efficient than kmemdup_nul() if > the size is known exactly. > > The description of kstrndup() already suggested: > Note: Use kmemdup_nul() instead if the size is known exactly. > > Signed-off-by: Xianting Tian <xianting_tian@126.com> Thanks for the patch but I think it is not ideal. The thing is that s_mount_opt is actually a NUL terminated string (we are just careful and don't rely on that to avoid problems when the fs is corrupted). So it is possibly shorter than those 64 bytes reserved for it in the superblock and using kmemdup_nul() will allocate and copy more memory than strictly necessary. Honza > --- > fs/ext4/super.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 330957e..be37556 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -4016,7 +4016,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > } > > if (sbi->s_es->s_mount_opts[0]) { > - char *s_mount_opts = kstrndup(sbi->s_es->s_mount_opts, > + char *s_mount_opts = kmemdup_nul(sbi->s_es->s_mount_opts, > sizeof(sbi->s_es->s_mount_opts), > GFP_KERNEL); > if (!s_mount_opts) > -- > 1.8.3.1 >
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 330957e..be37556 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4016,7 +4016,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } if (sbi->s_es->s_mount_opts[0]) { - char *s_mount_opts = kstrndup(sbi->s_es->s_mount_opts, + char *s_mount_opts = kmemdup_nul(sbi->s_es->s_mount_opts, sizeof(sbi->s_es->s_mount_opts), GFP_KERNEL); if (!s_mount_opts)
kmemdup_nul() is more efficient than kmemdup_nul() if the size is known exactly. The description of kstrndup() already suggested: Note: Use kmemdup_nul() instead if the size is known exactly. Signed-off-by: Xianting Tian <xianting_tian@126.com> --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)