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.
When the end of the requested region falls within an extent boundary then we
print the whole extent (i.e. return all the information that the kernel has given
us). When the end offset falls within a hole then the printed hole range is
truncated to the requested one since we do not have information how long the
hole is.
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
[sandeen: simplify/rewrite ranged logic]
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
V6: <sandeen>
* Update V5 changelog re: printed extents & end of range ;)
* rename "last" to "done"
* simplify loop control by setting done=1 in inner loop for all terminal conditions
* update manpage re: behavior details for ranged queries
V5:
* Now based on Eric's simpler approach.
* Fix printed-extent counting in print_plain & print_verbose
* Change while loop conditions to stop if full range has been mapped
V4:
* Don't do any fiemap processing if passed offset is past EOF. Filesystems
might have custom handling for this. XFS for example pretends there is a
hole.
* Restore offset/len handling to using the optional params at the end of
getopt and not using an additional '-r' param
V3:
* Fixed a bug where incorrect extent index was shown if we didn't print a
hole. This was due to statically returning 2 at the end of print_(plain|verbose)
Now, the actual number of printed extents inside the 2 functions is used.
This bug is visible only with the -r parameter
* Fixed a bug where 1 additional extent would be printed. This was a result of
the aforementioned bug fix, since now printing function can return 1 and still
have printed an extent and no hole. This can happen when you use -r parameter,
this is now fixed and a comment explaining it is put.
* Reworked the handling of the new params by making them arguments to the
-r parameter.
V2:
* Incorporated Daricks feedback - removed variables which weren't introduced
until the next patch as a result the build with this patch was broken. This is
fixed now
diff --git a/io/fiemap.c b/io/fiemap.c
index bdcfacd..2f12652 100644
--- a/io/fiemap.c
+++ b/io/fiemap.c
@@ -49,6 +49,8 @@ fiemap_help(void)
" -l -- also displays the length of each extent in 512-byte blocks.\n"
" -n -- query n extents.\n"
" -v -- Verbose information\n"
+" offset is the starting offset to map, and is optional. If offset is\n"
+" specified, mapping length may (optionally) be specified as well."
"\n"));
}
@@ -101,6 +103,7 @@ print_verbose(
char lbuf[48];
char bbuf[48];
char flgbuf[16];
+ int num_printed = 0;
llast = BTOBBT(last_logical);
lstart = BTOBBT(extent->fe_logical);
@@ -118,14 +121,15 @@ print_verbose(
flg_w, _("FLAGS"));
}
- if (lstart != llast) {
+ if (lstart > llast) {
print_hole(foff_w, boff_w, tot_w, cur_extent, 0, false, llast,
lstart);
cur_extent++;
+ num_printed++;
}
if (cur_extent == max_extents)
- return 1;
+ return num_printed;
snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:",
(unsigned long long)lstart, lstart + len - 1ULL);
@@ -135,7 +139,9 @@ print_verbose(
printf("%4d: %-*s %-*s %*llu %*s\n", cur_extent, foff_w, lbuf,
boff_w, bbuf, tot_w, (unsigned long long)len, flg_w, flgbuf);
- return 2;
+ num_printed++;
+
+ return num_printed;
}
static int
@@ -149,29 +155,33 @@ print_plain(
__u64 llast;
__u64 block;
__u64 len;
+ int num_printed = 0;
llast = BTOBBT(last_logical);
lstart = BTOBBT(extent->fe_logical);
len = BTOBBT(extent->fe_length);
block = BTOBBT(extent->fe_physical);
- if (lstart != llast) {
+ if (lstart > llast) {
print_hole(0, 0, 0, cur_extent, lflag, true, llast, lstart);
cur_extent++;
+ num_printed++;
}
if (cur_extent == max_extents)
- return 1;
+ return num_printed;
printf("\t%d: [%llu..%llu]: %llu..%llu", cur_extent,
(unsigned long long)lstart, lstart + len - 1ULL,
(unsigned long long)block, block + len - 1ULL);
+ num_printed++;
+
if (lflag)
printf(_(" %llu blocks\n"), (unsigned long long)len);
else
printf("\n");
- return 2;
+ return num_printed;
}
/*
@@ -222,7 +232,7 @@ fiemap_f(
char **argv)
{
struct fiemap *fiemap;
- int last = 0;
+ int done = 0;
int lflag = 0;
int vflag = 0;
int fiemap_flags = FIEMAP_FLAG_SYNC;
@@ -235,9 +245,15 @@ fiemap_f(
int boff_w = 16;
int tot_w = 5; /* 5 since its just one number */
int flg_w = 5;
- __u64 last_logical = 0;
+ __u64 last_logical = 0; /* last extent offset handled */
+ off64_t start_offset = 0; /* mapping start */
+ off64_t length = -1LL; /* mapping length */
+ off64_t range_end = -1LL; /* mapping end*/
+ size_t fsblocksize, fssectsize;
struct stat st;
+ init_cvtnum(&fsblocksize, &fssectsize);
+
while ((c = getopt(argc, argv, "aln:v")) != EOF) {
switch (c) {
case 'a':
@@ -257,6 +273,27 @@ fiemap_f(
}
}
+ /* Range start (optional) */
+ 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++;
+ }
+
+ /* Range length (optional if range start was specified) */
+ if (optind < argc) {
+ length = cvtnum(fsblocksize, fssectsize, argv[optind]);
+ if (length < 0) {
+ printf("non-numeric len argument -- %s\n", argv[optind]);
+ return 0;
+ }
+ range_end = start_offset + length;
+ }
+
map_size = sizeof(struct fiemap) +
(EXTENT_BATCH * sizeof(struct fiemap_extent));
fiemap = malloc(map_size);
@@ -269,12 +306,11 @@ fiemap_f(
printf("%s:\n", file->name);
- while (!last && (cur_extent != max_extents)) {
-
+ while (!done) {
memset(fiemap, 0, map_size);
fiemap->fm_flags = fiemap_flags;
fiemap->fm_start = last_logical;
- fiemap->fm_length = -1LL;
+ fiemap->fm_length = range_end - last_logical;
fiemap->fm_extent_count = EXTENT_BATCH;
ret = ioctl(file->fd, FS_IOC_FIEMAP, (unsigned long)fiemap);
@@ -314,13 +350,23 @@ fiemap_f(
cur_extent += num_printed;
last_logical = extent->fe_logical + extent->fe_length;
+ /* Kernel has told us there are no more extents */
if (extent->fe_flags & FIEMAP_EXTENT_LAST) {
- last = 1;
+ done = 1;
+ break;
+ }
+
+ /* We have exhausted the requested range */
+ if (last_logical >= range_end) {
+ done = 1;
break;
}
- if (cur_extent == max_extents)
+ /* We have printed requested nr of extents */
+ if (cur_extent == max_extents) {
+ done = 1;
break;
+ }
}
}
@@ -336,9 +382,12 @@ fiemap_f(
return 0;
}
- if (cur_extent && last_logical < st.st_size)
+ /* Print last hole to EOF or to end of requested range */
+ range_end = min((uint64_t)range_end, st.st_size);
+
+ if (cur_extent && last_logical < range_end)
print_hole(foff_w, boff_w, tot_w, cur_extent, lflag, !vflag,
- BTOBBT(last_logical), BTOBBT(st.st_size));
+ BTOBBT(last_logical), BTOBBT(range_end));
out:
free(fiemap);
@@ -353,7 +402,7 @@ 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] [offset [len]]");
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 9bf1a47..fabf92f 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -304,11 +304,23 @@ 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.
+.PP
+.RS
+Optionally, this command also supports passing the start offset
+from where to begin the mapping and the length of that region.
+The kernel will return any full extents which intersect with the requested
+range, and the
+.B fiemap
+command will print them in their entirety. If the requested range starts
+or ends in a hole,
+.B fiemap
+will print the hole, truncated to the requested range.
+.RE
.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
--
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
