Currently the ext2fs_check_mount_point() will use the open(O_EXCL) check
on linux after all the other checks are done. However it is not
necessary to check mntent if open(O_EXCL) succeeds because it means that
the device is not mounted.
Moreover the commit ea4d53b7 introduced a regression where a following
set of commands fails:
vgcreate mygroup /dev/sda
lvcreate -L 1G -n lvol0 mygroup
mkfs.ext4 /dev/mygroup/lvol0
mount /dev/mygroup/lvol0 /mnt
lvrename /dev/mygroup/lvol0 /dev/mygroup/lvol1
lvcreate -L 1G -n lvol0 mygroup
mkfs.ext4 /dev/mygroup/lvol0 <<<--- This fails
It fails because it thinks that /dev/mygroup/lvol0 is mounted because
the device name in /proc/mounts is not updated following the lvrename.
Move the open(O_EXCL) check before the mntent check and return
immediatelly if the device is not busy.
Fixes: ea4d53b7 ("libext2fs/ismounted.c: check device id in advance to skip false device names")
Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
Reported-by: Zdenek Kabelac <zkabelac@xxxxxxxxxx>
Reported-by: Karel Zak <kzak@xxxxxxxxxx>
Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
---
lib/ext2fs/ismounted.c | 42 +++++++++++++++++++++++++++---------------
1 file changed, 27 insertions(+), 15 deletions(-)
diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c
index c0215692..46d330d9 100644
--- a/lib/ext2fs/ismounted.c
+++ b/lib/ext2fs/ismounted.c
@@ -352,6 +352,7 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
char *mtpt, int mtlen)
{
errcode_t retval = 0;
+ int busy = 0;
if (getenv("EXT2FS_PRETEND_RO_MOUNT")) {
*mount_flags = EXT2_MF_MOUNTED | EXT2_MF_READONLY;
@@ -366,6 +367,30 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
return 0;
}
+#ifdef __linux__ /* This only works on Linux 2.6+ systems */
+ {
+ struct stat st_buf;
+
+ if (stat(device, &st_buf) == 0 &&
+ ext2fsP_is_disk_device(st_buf.st_mode)) {
+ int fd = open(device, O_RDONLY | O_EXCL);
+
+ if (fd >= 0) {
+ /*
+ * The device is not busy so it's
+ * definitelly not mounted. No need to
+ * to perform any more checks.
+ */
+ close(fd);
+ *mount_flags = 0;
+ return 0;
+ } else if (errno == EBUSY) {
+ busy = 1;
+ }
+ }
+ }
+#endif
+
if (is_swap_device(device)) {
*mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
strncpy(mtpt, "<swap>", mtlen);
@@ -386,21 +411,8 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
if (retval)
return retval;
-#ifdef __linux__ /* This only works on Linux 2.6+ systems */
- {
- struct stat st_buf;
-
- if (stat(device, &st_buf) == 0 &&
- ext2fsP_is_disk_device(st_buf.st_mode)) {
- int fd = open(device, O_RDONLY | O_EXCL);
-
- if (fd >= 0)
- close(fd);
- else if (errno == EBUSY)
- *mount_flags |= EXT2_MF_BUSY;
- }
- }
-#endif
+ if (busy)
+ *mount_flags |= EXT2_MF_BUSY;
return 0;
}
--
2.21.1
