On Thu, Oct 19, 2017 at 01:34:41PM +0300, Nikolay Borisov wrote:
> Currently the fiemap implementation of xfs_io doesn't support making ranged
> queries. This patch implements two optional arguments which take the starting
> offset and the length of the region to be queried. The impelmentation also
> calculates printed holes as an extent for the purpose of terminating the query.
>
> I.e. if we create a file with the following layout :
>
> xfs_io -f -c "falloc 0 32k" -c "fpunch 0 4k" -c "fpunch 8k 4k" \
> -c "fpunch 28k 4k" -c "fiemap" fragmented-file
>
> H D H D H
> |--------|--------|---------|--------------|-----------------|
> 0 4k 8k 12k 28k 32k
>
> Then the output is :
>
> xfs_io -c "fiemap 0 10k" fragmented-file
> fragmented-file:
> 0: [0..7]: hole
> 1: [8..15]: 897844104..897844111
> 2: [16..23]: hole
>
> xfs_io -c "fiemap 0" fragmented-file
> fragmented-file:
> 0: [0..7]: hole
> 1: [8..15]: 897844104..897844111
> 2: [16..23]: hole
> 3: [24..55]: 897844120..897844151
> 4: [56..63]: hole
>
> xfs_io -c "fiemap 10k 5k" fragmented-file
> fragmented-file:
> 0: [20..23]: hole
> 1: [24..55]: 897844120..897844151
>
> xfs_io -c "fiemap 10k 18k" fragmented-file
> fragmented-file:
> 0: [20..23]: hole
> 1: [24..55]: 897844120..897844151
> 2: [56..63]: hole
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> io/fiemap.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++---------
> man/man8/xfs_io.8 | 5 +++--
> 2 files changed, 54 insertions(+), 12 deletions(-)
>
> diff --git a/io/fiemap.c b/io/fiemap.c
> index e6fd66da753d..844741cb07d3 100644
> --- a/io/fiemap.c
> +++ b/io/fiemap.c
> @@ -27,6 +27,8 @@
>
> static cmdinfo_t fiemap_cmd;
> static int max_extents = -1;
> +static __u64 covered_length = 0;
> +static bool range_limit = false;
>
> static void
> fiemap_help(void)
> @@ -79,7 +81,7 @@ print_hole(
> boff_w, _("hole"), tot_w, lstart - llast);
> }
>
> -
> + covered_length += BBTOB(lstart - llast);
> }
>
> static int
> @@ -90,7 +92,8 @@ print_verbose(
> int tot_w,
> int flg_w,
> int cur_extent,
> - __u64 last_logical)
> + __u64 last_logical,
> + __u64 limit)
> {
> __u64 lstart;
> __u64 llast;
> @@ -122,7 +125,7 @@ print_verbose(
> cur_extent++;
> }
>
> - if (cur_extent == max_extents)
> + if (cur_extent == max_extents || (range_limit && covered_length >= limit))
> return 1;
>
> snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", lstart,
> @@ -140,7 +143,8 @@ print_plain(
> struct fiemap_extent *extent,
> int lflag,
> int cur_extent,
> - __u64 last_logical)
> + __u64 last_logical,
> + __u64 limit)
> {
> __u64 lstart;
> __u64 llast;
> @@ -157,7 +161,7 @@ print_plain(
> cur_extent++;
> }
>
> - if (cur_extent == max_extents)
> + if (cur_extent == max_extents || (range_limit && covered_length >= limit))
As mentioned on IRC, I don't think it's correct to compare
covered_length against limit here. If we want to fiemap blocks 200-300
we'd issue the command "fiemap 200k 100k", after which start_offset =
200, len = 100, and stop_offset = 300. We start the loop and
covered_length = 0, and at this point we end up comparing
(range_limit && covered_length >= limit) => (true && 0 >= 300)....
> return 1;
>
> printf("\t%d: [%llu..%llu]: %llu..%llu", cur_extent,
> @@ -211,6 +215,7 @@ calc_print_format(
> }
> }
>
> +
> int
> fiemap_f(
> int argc,
> @@ -231,8 +236,14 @@ fiemap_f(
> int tot_w = 5; /* 5 since its just one number */
> int flg_w = 5;
> __u64 last_logical = 0;
> + __u64 len = -1LL;
> + __u64 stop_offset = -1LL;
> + off64_t start_offset = 0;
> + size_t fsblocksize, fssectsize;
> struct stat st;
>
> + init_cvtnum(&fsblocksize, &fssectsize);
> +
> while ((c = getopt(argc, argv, "aln:v")) != EOF) {
> switch (c) {
> case 'a':
> @@ -252,6 +263,27 @@ fiemap_f(
> }
> }
>
> + if (optind < argc) {
> + start_offset = cvtnum(fsblocksize, fssectsize, argv[optind]);
> + if (start_offset < 0) {
> + printf("non-numeric offset argument -- %s\n", argv[optind]);
> + return 0;
> + }
> + last_logical = start_offset;
> + optind++;
> + }
> +
> + if (optind < argc) {
> + off64_t length = cvtnum(fsblocksize, fssectsize, argv[optind]);
> + if (length < 0) {
> + printf("non-numeric len argument -- %s\n", argv[optind]);
> + return 0;
> + }
> + len = length;
> + stop_offset = start_offset + len;
> + range_limit = true;
> + }
> +
> map_size = sizeof(struct fiemap) +
> (EXTENT_BATCH * sizeof(struct fiemap_extent));
> fiemap = malloc(map_size);
> @@ -269,7 +301,7 @@ fiemap_f(
> memset(fiemap, 0, map_size);
> fiemap->fm_flags = fiemap_flags;
> fiemap->fm_start = last_logical;
> - fiemap->fm_length = -1LL;
> + fiemap->fm_length = len;
Need to shorten len as we go around the loop.
> fiemap->fm_extent_count = EXTENT_BATCH;
>
> ret = ioctl(file->fd, FS_IOC_FIEMAP, (unsigned long)fiemap);
> @@ -300,14 +332,18 @@ fiemap_f(
> num_printed = print_verbose(extent, foff_w,
> boff_w, tot_w,
> flg_w, cur_extent,
> - last_logical);
> + last_logical,
> + stop_offset);
> } else
> num_printed = print_plain(extent, lflag,
> cur_extent,
> - last_logical);
> + last_logical,
> + stop_offset);
>
> cur_extent += num_printed;
> last_logical = extent->fe_logical + extent->fe_length;
> + if (num_printed == 2)
> + covered_length += extent->fe_length;
>
> if (extent->fe_flags & FIEMAP_EXTENT_LAST) {
> last = 1;
> @@ -316,6 +352,9 @@ fiemap_f(
>
> if (cur_extent == max_extents)
> break;
> +
> + if (range_limit && covered_length >= start_offset + len)
> + goto out;
> }
> }
>
> @@ -331,9 +370,11 @@ fiemap_f(
> return 0;
> }
>
> - if (cur_extent && last_logical < st.st_size)
> + if (cur_extent && last_logical < st.st_size &&
> + (!range_limit || covered_length < start_offset + len)) {
covered_length < stop_offset?
> print_hole(foff_w, boff_w, tot_w, cur_extent, lflag, !vflag,
> BTOBBT(last_logical), BTOBBT(st.st_size));
> + }
>
> out:
> free(fiemap);
> @@ -348,7 +389,7 @@ fiemap_init(void)
> fiemap_cmd.argmin = 0;
> fiemap_cmd.argmax = -1;
> fiemap_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
> - fiemap_cmd.args = _("[-alv] [-n nx]");
> + fiemap_cmd.args = _("[-alv] [-n nx] [start offset [len]]");
[offset [len]]
Otherwise it sounds like fiemap takes three parameters.
> fiemap_cmd.oneline = _("print block mapping for a file");
> fiemap_cmd.help = fiemap_help;
>
> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> index 0fd9b951199c..27f1ae163913 100644
> --- a/man/man8/xfs_io.8
> +++ b/man/man8/xfs_io.8
> @@ -295,11 +295,12 @@ Prints the block mapping for the current open file. Refer to the
> .BR xfs_bmap (8)
> manual page for complete documentation.
> .TP
> -.BI "fiemap [ \-alv ] [ \-n " nx " ]"
> +.BI "fiemap [ \-alv ] [ \-n " nx " ] [ " offset " [ " len " ]]"
> Prints the block mapping for the current open file using the fiemap
> ioctl. Options behave as described in the
> .BR xfs_bmap (8)
> -manual page.
> +manual page. Optionally, this command also supports passing the start offset
> +from where to begin the fiemap and the length of that region.
New sentences should start on their own line, per linux-manpages custom.
(Or maybe not; we violate that plenty in xfsprogs land...)
Also, fstests testcases needed.
--D
> .TP
> .BI "fsmap [ \-d | \-l | \-r ] [ \-m | \-v ] [ \-n " nx " ] [ " start " ] [ " end " ]
> Prints the mapping of disk blocks used by the filesystem hosting the current
> --
> 2.7.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
