fiemap's code was rather complicated for the simple task it did so this
patch aims to rectify the situation. The main changes are:
* Add a start_offset, len parameters, this allows to specify a range of the
file for which we want information, if those parameters are omitted the old
behavior is retained i.e. we get information for the whole file.
* We now always allocate as many struct fiemap_extent structs as necessary
to hold the information for the passed range (or the whole file)
* Made max_extents, blocksize global variables. They are never modified apart
from the initilization of the program.
* Eliminated the outer while loop, now that we allocate enough extent to
perform a single fiemap ioctl call there is no need for it.
* As a result the -n parameter works correctly for -n 1
* Also changed the way the last hole is being calculated, so far every time
the outter while loop finished the extenet from last_logical .. file size would
be output as a hole. This was not always true
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
---
Hello,
Here is more or less a major cleanup of the fiemap code. I've tested it with a
file with with the following layout HDHDHDHDHDHD (H - hole, D-data) and
varying permutation of the arguments and so far everthing seems to work as
expected. The biggest benefit I see is that the code is easier to follow now.
io/fiemap.c | 187 +++++++++++++++++++++++++++++-------------------------
man/man8/xfs_io.8 | 5 +-
2 files changed, 104 insertions(+), 88 deletions(-)
diff --git a/io/fiemap.c b/io/fiemap.c
index 75e882057362..5659f16d767d 100644
--- a/io/fiemap.c
+++ b/io/fiemap.c
@@ -24,6 +24,8 @@
#include "io.h"
static cmdinfo_t fiemap_cmd;
+static const __u64 blocksize = 512;
+static int max_extents = 0;
static void
fiemap_help(void)
@@ -34,6 +36,7 @@ fiemap_help(void)
"\n"
" Example:\n"
" 'fiemap -v' - tabular format verbose map\n"
+" 'fiemap 0 4k' - print fiemap extents for 0-4k range\n"
"\n"
" fiemap prints the map of disk blocks used by the current file.\n"
" The map lists each extent used by the file, as well as regions in the\n"
@@ -52,12 +55,10 @@ fiemap_help(void)
static void
print_verbose(
struct fiemap_extent *extent,
- int blocksize,
int foff_w,
int boff_w,
int tot_w,
int flg_w,
- int max_extents,
int *cur_extent,
__u64 *last_logical)
{
@@ -85,6 +86,7 @@ print_verbose(
flg_w, _("FLAGS"));
}
+
if (lstart != llast) {
snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", llast,
lstart - 1ULL);
@@ -94,7 +96,7 @@ print_verbose(
memset(lbuf, 0, sizeof(lbuf));
}
- if ((*cur_extent + 1) == max_extents)
+ if (max_extents && *cur_extent == max_extents)
return;
snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", lstart,
@@ -112,8 +114,6 @@ static void
print_plain(
struct fiemap_extent *extent,
int lflag,
- int blocksize,
- int max_extents,
int *cur_extent,
__u64 *last_logical)
{
@@ -137,7 +137,7 @@ print_plain(
(*cur_extent)++;
}
- if ((*cur_extent + 1) == max_extents)
+ if (max_extents && *cur_extent == max_extents)
return;
printf("\t%d: [%llu..%llu]: %llu..%llu", *cur_extent,
@@ -159,13 +159,12 @@ print_plain(
static void
calc_print_format(
struct fiemap *fiemap,
- __u64 blocksize,
int *foff_w,
int *boff_w,
int *tot_w,
int *flg_w)
{
- int i;
+ int i;
char lbuf[32];
char bbuf[32];
__u64 logical;
@@ -193,15 +192,28 @@ calc_print_format(
}
}
+static ssize_t
+get_extent_num(int fd, __u64 startoffset, __u64 len)
+{
+ struct fiemap fiemap = { 0 } ;
+ fiemap.fm_start = startoffset;
+ fiemap.fm_length = len;
+ if (ioctl(fd, FS_IOC_FIEMAP, (unsigned long)&fiemap) < 0) {
+ fprintf(stderr, _("%s: Failed to query fiemap extent count.\n"),
+ progname);
+ return -1;
+ }
+
+ return fiemap.fm_mapped_extents;
+}
+
int
fiemap_f(
int argc,
char **argv)
{
struct fiemap *fiemap;
- int max_extents = 0;
- int num_extents = 32;
- int last = 0;
+ int num_extents;
int lflag = 0;
int vflag = 0;
int fiemap_flags = FIEMAP_FLAG_SYNC;
@@ -210,24 +222,29 @@ fiemap_f(
int map_size;
int ret;
int cur_extent = 0;
- int foff_w = 16; /* 16 just for a good minimum range */
+ int foff_w = 16; /* 16 just for a good minimum range */
int boff_w = 16;
int tot_w = 5; /* 5 since its just one number */
int flg_w = 5;
- __u64 blocksize = 512;
__u64 last_logical = 0;
- struct stat st;
+ __u64 len = -1LL;
+ size_t fsblocksize, fssectsize;
+ off64_t start_offset = 0;
+ __u64 end_offset;
+ __u64 llast;
+ bool last_extent = false;
+
+ init_cvtnum(&fsblocksize, &fssectsize);
while ((c = getopt(argc, argv, "aln:v")) != EOF) {
switch (c) {
case 'a':
fiemap_flags |= FIEMAP_FLAG_XATTR;
break;
- case 'l':
- lflag = 1;
- break;
case 'n':
max_extents = atoi(optarg);
+ case 'l':
+ lflag = 1;
break;
case 'v':
vflag++;
@@ -237,8 +254,35 @@ fiemap_f(
}
}
- if (max_extents)
- num_extents = min(num_extents, max_extents);
+ 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;
+ }
+
+
+ end_offset = (start_offset + len) / blocksize;
+
+ ret = get_extent_num(file->fd, last_logical, len);
+ if (ret < 0) {
+ exitcode = 1;
+ return 0;
+ }
+ num_extents = ret;
+
map_size = sizeof(struct fiemap) +
(num_extents * sizeof(struct fiemap_extent));
fiemap = malloc(map_size);
@@ -251,92 +295,63 @@ fiemap_f(
printf("%s:\n", file->name);
- while (!last && ((cur_extent + 1) != max_extents)) {
- if (max_extents)
- num_extents = min(num_extents,
- max_extents - (cur_extent + 1));
-
- memset(fiemap, 0, map_size);
- fiemap->fm_flags = fiemap_flags;
- fiemap->fm_start = last_logical;
- fiemap->fm_length = -1LL;
- fiemap->fm_extent_count = num_extents;
-
- ret = ioctl(file->fd, FS_IOC_FIEMAP, (unsigned long)fiemap);
- if (ret < 0) {
- fprintf(stderr, "%s: ioctl(FS_IOC_FIEMAP) [\"%s\"]: "
- "%s\n", progname, file->name, strerror(errno));
- free(fiemap);
- exitcode = 1;
- return 0;
- }
+ memset(fiemap, 0, map_size);
+ fiemap->fm_flags = fiemap_flags;
+ fiemap->fm_start = last_logical;
+ fiemap->fm_length = len;
+ fiemap->fm_extent_count = num_extents;
- /* No more extents to map, exit */
- if (!fiemap->fm_mapped_extents)
- break;
+ ret = ioctl(file->fd, FS_IOC_FIEMAP, (unsigned long)fiemap);
+ if (ret < 0) {
+ fprintf(stderr, "%s: ioctl(FS_IOC_FIEMAP) [\"%s\"]: "
+ "%s\n", progname, file->name, strerror(errno));
+ free(fiemap);
+ exitcode = 1;
+ return 0;
+ }
+
+ for (i = 0; i < fiemap->fm_mapped_extents; i++) {
+ struct fiemap_extent *extent;
- for (i = 0; i < fiemap->fm_mapped_extents; i++) {
- struct fiemap_extent *extent;
-
- extent = &fiemap->fm_extents[i];
- if (vflag) {
- if (cur_extent == 0) {
- calc_print_format(fiemap, blocksize,
- &foff_w, &boff_w,
- &tot_w, &flg_w);
- }
-
- print_verbose(extent, blocksize, foff_w,
- boff_w, tot_w, flg_w,
- max_extents, &cur_extent,
- &last_logical);
- } else
- print_plain(extent, lflag, blocksize,
- max_extents, &cur_extent,
- &last_logical);
-
- if (extent->fe_flags & FIEMAP_EXTENT_LAST) {
- last = 1;
- break;
+ extent = &fiemap->fm_extents[i];
+ if (vflag) {
+ if (cur_extent == 0) {
+ calc_print_format(fiemap, &foff_w, &boff_w,
+ &tot_w, &flg_w);
}
- if ((cur_extent + 1) == max_extents)
- break;
- }
- }
+ print_verbose(extent, foff_w, boff_w, tot_w, flg_w,
+ &cur_extent, &last_logical);
+ } else
+ print_plain(extent, lflag, &cur_extent, &last_logical);
- if ((cur_extent + 1) == max_extents)
- goto out;
+ if (max_extents && cur_extent == max_extents)
+ goto out;
+
+ if (extent->fe_flags & FIEMAP_EXTENT_LAST)
+ last_extent = true;
- memset(&st, 0, sizeof(st));
- if (fstat(file->fd, &st)) {
- fprintf(stderr, "%s: fstat failed: %s\n", progname,
- strerror(errno));
- free(fiemap);
- exitcode = 1;
- return 0;
}
- if (cur_extent && last_logical < st.st_size) {
- char lbuf[32];
+ llast = last_logical / blocksize;
+ if (!last_extent && llast < end_offset) {
+ char lbuf[32];
+ __u64 difference = end_offset - llast;
+ snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:", llast, llast + difference);
- snprintf(lbuf, sizeof(lbuf), "[%llu..%llu]:",
- last_logical / blocksize, (st.st_size / blocksize) - 1);
if (vflag) {
printf("%4d: %-*s %-*s %*llu\n", cur_extent,
foff_w, lbuf, boff_w, _("hole"), tot_w,
- (st.st_size - last_logical) / blocksize);
+ difference);
} else {
printf("\t%d: %s %s", cur_extent, lbuf,
_("hole"));
if (lflag)
- printf(_(" %llu blocks\n"),
- (st.st_size - last_logical) / blocksize);
+ printf(_(" %llu blocks\n"), len / blocksize);
else
printf("\n");
}
}
-
out:
free(fiemap);
return 0;
@@ -350,7 +365,7 @@ 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]]");
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 273b9c54c52d..125db9181851 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.
.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
--
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