Hello, Zach
>> The original codes don't handle error gracefully and some places
>> forget to free memory. We can allocate memory before calling pretty_sizes(),
>> for example, we can use static memory allocation and we don't have to deal
>> with memory allocation fails.
>
> I agree that callers shouldn't have to know to free allocated memory.
>
> But I think that we can do better and not have callers need to worry
> about per-call string storage at all.
>
> How about something like this?
Yeah, much better than mine!
Acked-by: Wang Shilong <wangsl.fnst@xxxxxxxxxxxxxx>
Thanks,
Wang
>
> - z
>
> From bea92d06d98827af30518aa800428c0b2a8be101 Mon Sep 17 00:00:00 2001
> From: Zach Brown <zab@xxxxxxxxxx>
> Date: Tue, 9 Jul 2013 12:43:57 -0700
> Subject: [PATCH] btrfs-progs: per-thread, per-call pretty buffer
>
> We don't need callers to manage string storage for each pretty_sizes()
> call. We can use a macro to have per-thread and per-call static storage
> so that pretty_sizes() can be used as many times as needed in printf()
> arguments without requiring a bunch of supporting variables.
>
> This lets us have a natural interface at the cost of requiring __thread
> and TLS from gcc and a small amount of static storage. This seems
> better than the current code or doing something with illegible format
> specifier macros.
>
> Signed-off-by: Zach Brown <zab@xxxxxxxxxx>
> ---
> cmds-filesystem.c | 27 +++++++++------------------
> cmds-scrub.c | 8 ++++----
> mkfs.c | 4 +---
> utils.c | 17 +++++++++--------
> utils.h | 10 +++++++++-
> 5 files changed, 32 insertions(+), 34 deletions(-)
>
> diff --git a/cmds-filesystem.c b/cmds-filesystem.c
> index f41a72a..8d1c5c2 100644
> --- a/cmds-filesystem.c
> +++ b/cmds-filesystem.c
> @@ -111,8 +111,6 @@ static int cmd_df(int argc, char **argv)
>
> for (i = 0; i < sargs->total_spaces; i++) {
> char description[80];
> - char *total_bytes;
> - char *used_bytes;
> int written = 0;
> u64 flags = sargs->spaces[i].flags;
>
> @@ -155,10 +153,9 @@ static int cmd_df(int argc, char **argv)
> written += 7;
> }
>
> - total_bytes = pretty_sizes(sargs->spaces[i].total_bytes);
> - used_bytes = pretty_sizes(sargs->spaces[i].used_bytes);
> - printf("%s: total=%s, used=%s\n", description, total_bytes,
> - used_bytes);
> + printf("%s: total=%s, used=%s\n", description,
> + pretty_sizes(sargs->spaces[i].total_bytes),
> + pretty_sizes(sargs->spaces[i].used_bytes));
> }
> close(fd);
> free(sargs);
> @@ -192,7 +189,6 @@ static void print_one_uuid(struct btrfs_fs_devices *fs_devices)
> char uuidbuf[37];
> struct list_head *cur;
> struct btrfs_device *device;
> - char *super_bytes_used;
> u64 devs_found = 0;
> u64 total;
>
> @@ -204,25 +200,20 @@ static void print_one_uuid(struct btrfs_fs_devices *fs_devices)
> else
> printf("Label: none ");
>
> - super_bytes_used = pretty_sizes(device->super_bytes_used);
>
> total = device->total_devs;
> printf(" uuid: %s\n\tTotal devices %llu FS bytes used %s\n", uuidbuf,
> - (unsigned long long)total, super_bytes_used);
> -
> - free(super_bytes_used);
> + (unsigned long long)total,
> + pretty_sizes(device->super_bytes_used));
>
> list_for_each(cur, &fs_devices->devices) {
> - char *total_bytes;
> - char *bytes_used;
> device = list_entry(cur, struct btrfs_device, dev_list);
> - total_bytes = pretty_sizes(device->total_bytes);
> - bytes_used = pretty_sizes(device->bytes_used);
> +
> printf("\tdevid %4llu size %s used %s path %s\n",
> (unsigned long long)device->devid,
> - total_bytes, bytes_used, device->name);
> - free(total_bytes);
> - free(bytes_used);
> + pretty_sizes(device->total_bytes),
> + pretty_sizes(device->bytes_used), device->name);
> +
> devs_found++;
> }
> if (devs_found < total) {
> diff --git a/cmds-scrub.c b/cmds-scrub.c
> index c0dc584..25f9ffd 100644
> --- a/cmds-scrub.c
> +++ b/cmds-scrub.c
> @@ -139,7 +139,6 @@ static void print_scrub_summary(struct btrfs_scrub_progress *p)
> {
> u64 err_cnt;
> u64 err_cnt2;
> - char *bytes;
>
> err_cnt = p->read_errors +
> p->csum_errors +
> @@ -151,10 +150,11 @@ static void print_scrub_summary(struct btrfs_scrub_progress *p)
> if (p->malloc_errors)
> printf("*** WARNING: memory allocation failed while scrubbing. "
> "results may be inaccurate\n");
> - bytes = pretty_sizes(p->data_bytes_scrubbed + p->tree_bytes_scrubbed);
> - printf("\ttotal bytes scrubbed: %s with %llu errors\n", bytes,
> +
> + printf("\ttotal bytes scrubbed: %s with %llu errors\n",
> + pretty_sizes(p->data_bytes_scrubbed + p->tree_bytes_scrubbed),
> max(err_cnt, err_cnt2));
> - free(bytes);
> +
> if (err_cnt || err_cnt2) {
> printf("\terror details:");
> PRINT_SCRUB_ERROR(p->read_errors, "read");
> diff --git a/mkfs.c b/mkfs.c
> index b412b7e..1a09d31 100644
> --- a/mkfs.c
> +++ b/mkfs.c
> @@ -1273,7 +1273,6 @@ int main(int ac, char **av)
> u64 num_of_meta_chunks = 0;
> u64 size_of_data = 0;
> u64 source_dir_size = 0;
> - char *pretty_buf;
> struct btrfs_super_block *super;
> u64 flags;
> int dev_cnt = 0;
> @@ -1525,8 +1524,7 @@ raid_groups:
> printf("fs created label %s on %s\n\tnodesize %u leafsize %u "
> "sectorsize %u size %s\n",
> label, first_file, nodesize, leafsize, sectorsize,
> - pretty_buf = pretty_sizes(btrfs_super_total_bytes(root->fs_info->super_copy)));
> - free(pretty_buf);
> + pretty_sizes(btrfs_super_total_bytes(root->fs_info->super_copy)));
>
> printf("%s\n", BTRFS_BUILD_VERSION);
> btrfs_commit_transaction(trans, root);
> diff --git a/utils.c b/utils.c
> index 7b4cd74..2688eb8 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -1153,12 +1153,13 @@ out:
>
> static char *size_strs[] = { "", "KB", "MB", "GB", "TB",
> "PB", "EB", "ZB", "YB"};
> -char *pretty_sizes(u64 size)
> +void pretty_size_snprintf(u64 size, char *str, size_t str_bytes)
> {
> int num_divs = 0;
> - int pretty_len = 16;
> float fraction;
> - char *pretty;
> +
> + if (str_bytes == 0)
> + return;
>
> if( size < 1024 ){
> fraction = size;
> @@ -1172,13 +1173,13 @@ char *pretty_sizes(u64 size)
> num_divs ++;
> }
>
> - if (num_divs >= ARRAY_SIZE(size_strs))
> - return NULL;
> + if (num_divs >= ARRAY_SIZE(size_strs)) {
> + str[0] = '\0';
> + return;
> + }
> fraction = (float)last_size / 1024;
> }
> - pretty = malloc(pretty_len);
> - snprintf(pretty, pretty_len, "%.2f%s", fraction, size_strs[num_divs]);
> - return pretty;
> + snprintf(str, str_bytes, "%.2f%s", fraction, size_strs[num_divs]);
> }
>
> /*
> diff --git a/utils.h b/utils.h
> index 3c17e14..03e4aee 100644
> --- a/utils.h
> +++ b/utils.h
> @@ -44,7 +44,15 @@ int check_mounted_where(int fd, const char *file, char *where, int size,
> struct btrfs_fs_devices **fs_devices_mnt);
> int btrfs_device_already_in_root(struct btrfs_root *root, int fd,
> int super_offset);
> -char *pretty_sizes(u64 size);
> +
> +void pretty_size_snprintf(u64 size, char *str, size_t str_bytes);
> +#define pretty_sizes(size) \
> + ({ \
> + static __thread char _str[16]; \
> + pretty_size_snprintf(size, _str, sizeof(_str)); \
> + _str; \
> + })
> +
> int get_mountpt(char *dev, char *mntpt, size_t size);
> int btrfs_scan_block_devices(int run_ioctl);
> u64 parse_size(char *s);
> --
> 1.7.11.7
>
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