korg/e2fsprogs
0
0
Fork 0
mirror of https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git synced 2024-12-02 22:43:48 +08:00
Code Issues Packages Projects Releases Wiki Activity

libext2fs: check open(O_EXCL) first in ismounted.c

Browse Source 
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@redhat.com>
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Reported-by: Karel Zak <kzak@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Lukas Czerner 2020-03-03 14:53:48 +01:00 committed by Theodore Ts'o
parent f106b01c98
commit ca84539d5f
1 changed files with 27 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
lib/ext2fs/ismounted.c
View File

@ -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;
}