| Message ID | 20180716125213.16767-1-yturgema@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | christophe varoqui |
| Headers | show |
On Mon, Jul 16, 2018 at 03:52:13PM +0300, Yuval Turgeman wrote: > When running `kpartx -d`, find_loop_by_file tries to compare the image's > realpath with the output from loopinfo.lo_name, which may hold only the > basename of the image, making kpartx exit without finding the loopdev > for the image. > > In case the original comparison fails, this patch will check the image's > realpath with the loop device's backing_file so that find_loop_by_file > will return the correct value. Looks good. Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com> > > Signed-off-by: Yuval Turgeman <yturgema@redhat.com> > --- > kpartx/lopart.c | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/kpartx/lopart.c b/kpartx/lopart.c > index 69c1eda1..9b652554 100644 > --- a/kpartx/lopart.c > +++ b/kpartx/lopart.c > @@ -69,6 +69,8 @@ char *find_loop_by_file(const char *filename) > struct loop_info loopinfo; > const char VIRT_BLOCK[] = "/sys/devices/virtual/block"; > char path[PATH_MAX]; > + char bf_path[PATH_MAX]; > + char backing_file[PATH_MAX]; > > dir = opendir(VIRT_BLOCK); > if (!dir) > @@ -122,6 +124,34 @@ char *find_loop_by_file(const char *filename) > found = realpath(path, NULL); > break; > } > + > + /* > + * filename is a realpath, while loopinfo.lo_name may hold just the > + * basename. If that's the case, try to match filename against the > + * backing_file entry for this loop entry > + */ > + if (snprintf(bf_path, PATH_MAX, "%s/%s/loop/backing_file", VIRT_BLOCK, > + dent->d_name) >= PATH_MAX) > + continue; > + > + fd = open(bf_path, O_RDONLY); > + if (fd < 0) > + continue; > + > + bytes_read = read(fd, backing_file, sizeof(backing_file) - 1); > + if (bytes_read <= 0) { > + close(fd); > + continue; > + } > + > + close(fd); > + > + backing_file[bytes_read-1] = '\0'; > + > + if (0 == strcmp(filename, backing_file)) { > + found = realpath(path, NULL); > + break; > + } > } > closedir(dir); > return found; > -- > 2.17.1 > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Mon, Jul 16, 2018 at 03:52:13PM +0300, Yuval Turgeman wrote: > When running `kpartx -d`, find_loop_by_file tries to compare the image's > realpath with the output from loopinfo.lo_name, which may hold only the > basename of the image, making kpartx exit without finding the loopdev > for the image. > > In case the original comparison fails, this patch will check the image's > realpath with the loop device's backing_file so that find_loop_by_file > will return the correct value. That seems like it does the same as my patch[1] from February, but in a more sane way. "Good" I did not follow up more on that :) /me will check if it solves the problem shortly. [1] https://www.redhat.com/archives/dm-devel/2018-February/msg00019.html
diff --git a/kpartx/lopart.c b/kpartx/lopart.c index 69c1eda1..9b652554 100644 --- a/kpartx/lopart.c +++ b/kpartx/lopart.c @@ -69,6 +69,8 @@ char *find_loop_by_file(const char *filename) struct loop_info loopinfo; const char VIRT_BLOCK[] = "/sys/devices/virtual/block"; char path[PATH_MAX]; + char bf_path[PATH_MAX]; + char backing_file[PATH_MAX]; dir = opendir(VIRT_BLOCK); if (!dir) @@ -122,6 +124,34 @@ char *find_loop_by_file(const char *filename) found = realpath(path, NULL); break; } + + /* + * filename is a realpath, while loopinfo.lo_name may hold just the + * basename. If that's the case, try to match filename against the + * backing_file entry for this loop entry + */ + if (snprintf(bf_path, PATH_MAX, "%s/%s/loop/backing_file", VIRT_BLOCK, + dent->d_name) >= PATH_MAX) + continue; + + fd = open(bf_path, O_RDONLY); + if (fd < 0) + continue; + + bytes_read = read(fd, backing_file, sizeof(backing_file) - 1); + if (bytes_read <= 0) { + close(fd); + continue; + } + + close(fd); + + backing_file[bytes_read-1] = '\0'; + + if (0 == strcmp(filename, backing_file)) { + found = realpath(path, NULL); + break; + } } closedir(dir); return found;
When running `kpartx -d`, find_loop_by_file tries to compare the image's realpath with the output from loopinfo.lo_name, which may hold only the basename of the image, making kpartx exit without finding the loopdev for the image. In case the original comparison fails, this patch will check the image's realpath with the loop device's backing_file so that find_loop_by_file will return the correct value. Signed-off-by: Yuval Turgeman <yturgema@redhat.com> --- kpartx/lopart.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)