On Wed, Nov 14, 2018 at 09:17:10PM +0800, Anand Jain wrote:
> Improve on describe_relocation() add a common helper function to describe
> the block groups.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> Reviewed-by: David Sterba <dsterba@xxxxxxxx>
> ---
> v4.1->v5: Initialize buf[128] to null.
> v4->v4.1: Use strcpy(buf, "|NONE"); as in the original
> v3->v4: Just pass full flag name in the define DESCRIBE_FLAG(flag,..),
> so that it can be used at couple of more places.
> Rename describe_block_groups() to btrfs_describe_block_groups().
> Drop useless return u32.
> v3: Born.
>
> fs/btrfs/relocation.c | 30 +++---------------------------
> fs/btrfs/volumes.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/volumes.h | 1 +
> 3 files changed, 47 insertions(+), 27 deletions(-)
>
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 924116f654a1..0373b3cc1d36 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -4184,37 +4184,13 @@ static struct reloc_control *alloc_reloc_control(void)
> static void describe_relocation(struct btrfs_fs_info *fs_info,
> struct btrfs_block_group_cache *block_group)
> {
> - char buf[128]; /* prefixed by a '|' that'll be dropped */
> - u64 flags = block_group->flags;
> + char buf[128] = {'\0'};
>
> - /* Shouldn't happen */
> - if (!flags) {
> - strcpy(buf, "|NONE");
> - } else {
> - char *bp = buf;
> -
> -#define DESCRIBE_FLAG(f, d) \
> - if (flags & BTRFS_BLOCK_GROUP_##f) { \
> - bp += snprintf(bp, buf - bp + sizeof(buf), "|%s", d); \
> - flags &= ~BTRFS_BLOCK_GROUP_##f; \
> - }
> - DESCRIBE_FLAG(DATA, "data");
> - DESCRIBE_FLAG(SYSTEM, "system");
> - DESCRIBE_FLAG(METADATA, "metadata");
> - DESCRIBE_FLAG(RAID0, "raid0");
> - DESCRIBE_FLAG(RAID1, "raid1");
> - DESCRIBE_FLAG(DUP, "dup");
> - DESCRIBE_FLAG(RAID10, "raid10");
> - DESCRIBE_FLAG(RAID5, "raid5");
> - DESCRIBE_FLAG(RAID6, "raid6");
> - if (flags)
> - snprintf(bp, buf - bp + sizeof(buf), "|0x%llx", flags);
> -#undef DESCRIBE_FLAG
> - }
> + btrfs_describe_block_groups(block_group->flags, buf, sizeof(buf));
>
> btrfs_info(fs_info,
> "relocating block group %llu flags %s",
> - block_group->key.objectid, buf + 1);
> + block_group->key.objectid, buf);
> }
>
> /*
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index f435d397019e..12b3d0625c6a 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -123,6 +123,49 @@ const char *get_raid_name(enum btrfs_raid_types type)
> return btrfs_raid_array[type].raid_name;
> }
>
> +void btrfs_describe_block_groups(u64 bg_flags, char *buf, u32 size_buf)
> +{
> + int i;
> + int ret;
> + char *bp = buf;
> + u64 flags = bg_flags;
> + u32 size_bp = size_buf;
> +
> + if (!flags) {
> + strcpy(bp, "NONE");
> + return;
> + }
> +
> +#define DESCRIBE_FLAG(f, d) \
Macro arguments should be in ( ) in the body
> + do { \
> + if (flags & f) { \
> + ret = snprintf(bp, size_bp, "%s|", d); \
> + if (ret < 0 || ret >= size_bp) \
> + return; \
Ok, this seems to be safe. snprintf will not write more than size_bp and
this will be caught if it overflows.
The return is obscured by the macro, I'd rather make it more visible
that there is a potential change in the code flow. The proposed change:
goto out_overflow;
...
and define out_overflow at the end of function. Same for the other
helper macros.
Also please align the backslashes of the macro a few tabs to the right.
> + size_bp -= ret; \
> + bp += ret; \
> + flags &= ~f; \
> + } \
> + } while (0)
