On Mon, 2018-02-05 at 09:58 +0100, Julian Andres Klode wrote: > Commit 9bdfa3eb8e24b668e6c2bb882cddb0ccfe23ed5b changed kpartx > to lookup files by absolute path, using realpath(). This introduced > a regression when part of the filename where symbolic links. While > the kernel stores the absolute path to the backing file, it does not > resolve symbolic links, and hence kpartx would fail to find the > loopback > device because it resolves symbolic links when deleting. > > This introduces two workarounds in find_loop_by_file() > > (1) We match against the specified file name as is as well > (2) We canonicalize the loopinfo.lo_name and match the canonicalized > filename > against that. > > Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/multipath-tools > /+bug/1747044 > Signed-off-by: Julian Andres Klode <[email protected]> > --- > kpartx/kpartx.c | 8 +------- > kpartx/lopart.c | 12 +++++++++++- > 2 files changed, 12 insertions(+), 8 deletions(-) > > diff --git a/kpartx/kpartx.c b/kpartx/kpartx.c > index 442b6bd9..c1af1c5e 100644 > --- a/kpartx/kpartx.c > +++ b/kpartx/kpartx.c > @@ -327,13 +327,7 @@ main(int argc, char **argv){ > > if (S_ISREG (buf.st_mode)) { > /* already looped file ? */ > - char rpath[PATH_MAX]; > - if (realpath(device, rpath) == NULL) { > - fprintf(stderr, "Error: %s: %s\n", device, > - strerror(errno)); > - exit (1); > - } > - loopdev = find_loop_by_file(rpath); > + loopdev = find_loop_by_file(device); > > if (!loopdev && what == DELETE) > exit (0); > diff --git a/kpartx/lopart.c b/kpartx/lopart.c > index 02b29e8c..26b2678c 100644 > --- a/kpartx/lopart.c > +++ b/kpartx/lopart.c > @@ -69,6 +69,13 @@ 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 rfilename[PATH_MAX]; > + char rloopfilename[PATH_MAX]; > + if (realpath(filename, rfilename) == NULL) { > + fprintf(stderr, "Error: %s: %s\n", filename, > + strerror(errno)); > + exit (1); > + } > > dir = opendir(VIRT_BLOCK); > if (!dir) > @@ -117,7 +124,10 @@ char *find_loop_by_file(const char *filename) > > close (fd); > > - if (0 == strcmp(filename, loopinfo.lo_name)) { > + if (0 == strcmp(filename, loopinfo.lo_name) || > + 0 == strcmp(rfilename, loopinfo.lo_name) || > + (realpath(loopinfo.lo_name, rloopfilename) && > + 0 == strcmp(rfilename, rloopfilename))) { > found = realpath(path, NULL); > break; > }
That "if x matches y or x matches y' or x' matches y" feels like guesswork. Can't we simply call realpath() on both loopinfo.lo_name and filename, and compare the two? Martin -- Dr. Martin Wilck <[email protected]>, Tel. +49 (0)911 74053 2107 SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg) -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
