NACK haven't noticed that FIEMAP also doesn't count holes
ignore
On 2024-09-03 11:37:30, Andrey Albershteyn wrote:
> FS_IOC_FIEMAP has an option to return total number of extents
> without copying each one of them. This could be pretty handy for
> checking if large file is heavily fragmented. The same can be done
> with calling FS_IOC_FIEMAP and counting lines with wc but
> FS_IOC_FIEMAP is limited to ~76mil extents (FIEMAP_MAX_EXTENTS). The
> other option is FS_IOC_FSGETXATTR which is much faster than
> iterating through all extents, but it doesn't include holes.
>
> Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx>
> ---
> io/fiemap.c | 27 +++++++++++++++++++++++----
> 1 file changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/io/fiemap.c b/io/fiemap.c
> index b41f71bfd027..d4e55a82f6db 100644
> --- a/io/fiemap.c
> +++ b/io/fiemap.c
> @@ -42,6 +42,13 @@ fiemap_help(void)
> "\n"));
> }
>
> +static void
> +print_total(
> + struct fiemap *fiemap)
> +{
> + printf("Extents total: %d\n", fiemap->fm_mapped_extents);
> +}
> +
> static void
> print_hole(
> int foff_w,
> @@ -223,9 +230,11 @@ fiemap_f(
> int done = 0;
> int lflag = 0;
> int vflag = 0;
> + int sflag = 0;
> int fiemap_flags = FIEMAP_FLAG_SYNC;
> int c;
> int i;
> + int ext_arr_size = 0;
> int map_size;
> int ret;
> int cur_extent = 0;
> @@ -242,7 +251,7 @@ fiemap_f(
>
> init_cvtnum(&fsblocksize, &fssectsize);
>
> - while ((c = getopt(argc, argv, "aln:v")) != EOF) {
> + while ((c = getopt(argc, argv, "aln:sv")) != EOF) {
> switch (c) {
> case 'a':
> fiemap_flags |= FIEMAP_FLAG_XATTR;
> @@ -253,6 +262,9 @@ fiemap_f(
> case 'n':
> max_extents = atoi(optarg);
> break;
> + case 's':
> + sflag++;
> + break;
> case 'v':
> vflag++;
> break;
> @@ -285,8 +297,9 @@ fiemap_f(
> range_end = start_offset + length;
> }
>
> - map_size = sizeof(struct fiemap) +
> - (EXTENT_BATCH * sizeof(struct fiemap_extent));
> + if (!sflag)
> + ext_arr_size = (EXTENT_BATCH * sizeof(struct fiemap_extent));
> + map_size = sizeof(struct fiemap) + ext_arr_size;
> fiemap = malloc(map_size);
> if (!fiemap) {
> fprintf(stderr, _("%s: malloc of %d bytes failed.\n"),
> @@ -302,7 +315,8 @@ fiemap_f(
> fiemap->fm_flags = fiemap_flags;
> fiemap->fm_start = last_logical;
> fiemap->fm_length = range_end - last_logical;
> - fiemap->fm_extent_count = EXTENT_BATCH;
> + if (!sflag)
> + fiemap->fm_extent_count = EXTENT_BATCH;
>
> ret = ioctl(file->fd, FS_IOC_FIEMAP, (unsigned long)fiemap);
> if (ret < 0) {
> @@ -313,6 +327,11 @@ fiemap_f(
> return 0;
> }
>
> + if (sflag) {
> + print_total(fiemap);
> + goto out;
> + }
> +
> /* No more extents to map, exit */
> if (!fiemap->fm_mapped_extents)
> break;
> --
> 2.44.1
>
--
- Andrey
