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It's always been a hassle that if an external journal's device number changes, the filesystem won't mount. And since boot-time enumeration can change, device number changes aren't unusual. The current mechanism to update the journal location is by passing in a mount option w/ a new devnum, but that's a hassle; it's a manual approach, fixing things after the fact. Adding a mount option, "-o journal_path=/dev/$DEVICE" would help, since then we can do i.e. # mount -o journal_path=/dev/disk/by-label/$JOURNAL_LABEL ... and it'll mount even if the devnum has changed, as shown here: # losetup /dev/loop0 journalfile # mke2fs -L mylabel-journal -O journal_dev /dev/loop0 # mkfs.ext3 -L mylabel -J device=/dev/loop0 /dev/sdb1 Change the journal device number: # losetup -d /dev/loop0 # losetup /dev/loop1 journalfile And today it will fail: # mount /dev/sdb1 /mnt/test mount: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so # dmesg | tail -n 1 [17343.240702] EXT3-fs (sdb1): error: couldn't read superblock of external journal But with this new mount option, we can specify the new path: # mount -o journal_path=/dev/loop1 /dev/sdb1 /mnt/test # (which does update the encoded device number, incidentally): # umount /dev/sdb1 # dumpe2fs -h /dev/sdb1 | grep "Journal device" dumpe2fs 1.41.12 (17-May-2010) Journal device: 0x0701 But best of all we can just always mount by journal-path, and it'll always work: # mount -o journal_path=/dev/disk/by-label/mylabel-journal /dev/sdb1 /mnt/test # So the journal_path option can be specified in fstab, and as long as the disk is available somewhere, and findable by label (or by UUID), we can mount. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> |
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.. | ||
caching | ||
configfs | ||
nfs | ||
pohmelfs | ||
9p.txt | ||
00-INDEX | ||
adfs.txt | ||
affs.txt | ||
afs.txt | ||
autofs4-mount-control.txt | ||
automount-support.txt | ||
befs.txt | ||
bfs.txt | ||
btrfs.txt | ||
ceph.txt | ||
cifs.txt | ||
coda.txt | ||
cramfs.txt | ||
debugfs.txt | ||
devpts.txt | ||
directory-locking | ||
dlmfs.txt | ||
dnotify_test.c | ||
dnotify.txt | ||
ecryptfs.txt | ||
efivarfs.txt | ||
exofs.txt | ||
ext2.txt | ||
ext3.txt | ||
ext4.txt | ||
f2fs.txt | ||
fiemap.txt | ||
files.txt | ||
fuse.txt | ||
gfs2-glocks.txt | ||
gfs2-uevents.txt | ||
gfs2.txt | ||
hfs.txt | ||
hfsplus.txt | ||
hpfs.txt | ||
inotify.txt | ||
isofs.txt | ||
jfs.txt | ||
Locking | ||
locks.txt | ||
logfs.txt | ||
Makefile | ||
mandatory-locking.txt | ||
ncpfs.txt | ||
nilfs2.txt | ||
ntfs.txt | ||
ocfs2.txt | ||
omfs.txt | ||
path-lookup.txt | ||
porting | ||
proc.txt | ||
qnx6.txt | ||
quota.txt | ||
ramfs-rootfs-initramfs.txt | ||
relay.txt | ||
romfs.txt | ||
seq_file.txt | ||
sharedsubtree.txt | ||
spufs.txt | ||
squashfs.txt | ||
sysfs-pci.txt | ||
sysfs-tagging.txt | ||
sysfs.txt | ||
sysv-fs.txt | ||
tmpfs.txt | ||
ubifs.txt | ||
udf.txt | ||
ufs.txt | ||
vfat.txt | ||
vfs.txt | ||
xfs-delayed-logging-design.txt | ||
xfs-self-describing-metadata.txt | ||
xfs.txt | ||
xip.txt |