ocfs2 support for blkid utility
PATCH 1/1 ocfs2 support for blkid utility
In a an email thread on the Data Center Linux (DCL) working group mailing list about a proposed requirement for persistant device naming, Theodore Ts'o noted that his blkid utility in the e2fsprog package could be used as part of a persistent device naming implementation.
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Quoted 5 lines · Rusty Lynch
Can you point me to some documentation on how to add support for other filesystems. I just recently started working with ocfs, and it looks like blkid is not picking up and partitions formated for ocfs.
No documentation, I'm afraid, although adding support for ocfs should be fairly straightforward. The relevant file is e2fsprogs/lib/blkid/probe.c. If the filesystem has a straightforward magic number, it can just be placed in the blk_magic type array:
/*
* Various filesystem magics that we can check for. Note that kboff and
* sboff are in kilobytes and bytes respectively. All magics are in
* byte strings so we don't worry about endian issues.
*/
static struct blkid_magic type_array[] = {
/* type kboff sboff len magic probe */
...
{ "xfs", 0, 0, 4, "XFSB", probe_xfs },
...
}The probe function (probe_xfs in this case) can also be used to do a more refined test. The probe function is responsible for setting the label and uuid information for the filesystem, or else returning a non-zero value if it turns out that the filesystem is not of the specified type. lib/blkid/probe.c probably could be more paranoid about identifying filesystems, but to date no one has reported any false positives so I haven't bothered to put in more stringent tests. (See the probe_reiserfs() function for an example of the sort of extra testing that can be done to make sure the superblock is consistent.) As always, patches are welcome. :-)
- Ted
P.S. I'm about to release a new e2fsprogs release soon, so if you have some additional filesystems that should be added (blkid currently supports ext2, ext3, jbd, jfs, xfs, reiserfs, minix, vfat, msdos, ntfs, hfs, vxfs, hpfs, sysv, romfs, bfs, cramfs, qnx4, udf, iso9660, and swap, with LABEL and/or UUID support for all filesystems that support such labelling), please let me know. I'm aiming for blkid to be as complete as possible.
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CUT
So... I downloaded the e2fsprog source tree and hacked the following patch that adds ocfs2 support.
In the probe_ocfs() function, buf contains the first kbytes of data from the disk, and I just grab the label, suggested mount point, and UUID by indexing into buf.
Some of the other probe functions define their super block structure in an e2fsprog header file, and then just cast buf to their own super block. Since ocfs2 structures are considerably more complex, I just went with the offset method.
This code would totally break if ocfs2 changes the layout of the first kbyte on disk. Are there any plans to change this?
Would anyone have a problem with me submitting this to the e2fsprogs project?
--rusty
home/rusty/probe.c renamed from probe.c +22 -0
@@ -312,6 +312,27 @@return 1 ; } +static int probe_ocfs(int fd __BLKID_ATTR((unused)), + blkid_cache cache __BLKID_ATTR((unused)), + blkid_dev dev, + struct blkid_magic *id __BLKID_ATTR((unused)), + unsigned char *buf) +{ +char *label =0 ; +char *mount_point =0 ; + +if (strlen ((char *) (buf +0x230 ))) + label = (char *) (buf +0x230 ); +blkid_set_tag (dev,"LABEL" , label,64 ); + +if (strlen ((char *) (buf +0x88 ))) + mount_point = (char *) (buf +0x88 ); +blkid_set_tag (dev,"MOUNT" , mount_point,128 ); + +set_uuid (dev, (char *)(buf +0x272 )); +return 0 ; +} +/* * BLKID_BLK_OFFS is at least as large as the highest bim_kboff defined * in the type_array table below + bim_kbalign.
@@ -371,6 +392,7 @@ { "swap", 0, 0x1ff6, 10, "SWAPSPACE2", 0 }, { "swap", 0, 0x3ff6, 10, "SWAP-SPACE", 0 }, { "swap", 0, 0x3ff6, 10, "SWAPSPACE2", 0 }, + { "ocfs2", 0, 8, 9, "OracleCFS", probe_ocfs }, { NULL, 0, 0, 0, NULL, NULL } };
PATCH 1/1 ocfs2 support for blkid utility
its actually in the redhat mount stuff, you can mount by label etc afaik it's in the standard one too, I remember even seeing it in manpages
Quoted 116 lines · Rusty Lynch
In a an email thread on the Data Center Linux (DCL) working group mailing list about a proposed requirement for persistant device naming, Theodore Ts'o noted that his blkid utility in the e2fsprog package could be used as part of a persistent device naming implementation.
<<<<<<<<<<<<<< CUT
Quoted 5 lines · Rusty Lynch
Can you point me to some documentation on how to add support for other filesystems. I just recently started working with ocfs, and it looks like blkid is not picking up and partitions formated for ocfs.
No documentation, I'm afraid, although adding support for ocfs should be fairly straightforward. The relevant file is
e2fsprogs/lib/blkid/probe.c. If the filesystem has a straightforward magic number, it can just be placed in theblk_magictype array:/*
* Various filesystem magics that we can check for. Note that kboff and
* sboff are in kilobytes and bytes respectively. All magics are in
* byte strings so we don't worry about endian issues.
*/
static structblkid_magictype_array[] = {
/* type kboff sboff len magic probe */... { "xfs", 0, 0, 4, "XFSB", probe_xfs }, ... }The probe function (
probe_xfsin this case) can also be used to do a more refined test. The probe function is responsible for setting the label and uuid information for the filesystem, or else returning a non-zero value if it turns out that the filesystem is not of the specified type.lib/blkid/probe.cprobably could be more paranoid about identifying filesystems, but to date no one has reported any false positives so I haven't bothered to put in more stringent tests. (See theprobe_reiserfs()function for an example of the sort of extra testing that can be done to make sure the superblock is consistent.) As always, patches are welcome. :-)- Ted
P.S. I'm about to release a new e2fsprogs release soon, so if you have some additional filesystems that should be added (blkid currently supports ext2, ext3, jbd, jfs, xfs, reiserfs, minix, vfat, msdos, ntfs, hfs, vxfs, hpfs, sysv, romfs, bfs, cramfs, qnx4, udf, iso9660, and swap, with LABEL and/or UUID support for all filesystems that support such labelling), please let me know. I'm aiming for blkid to be as complete as possible.Quoted 1 line
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So... I downloaded the e2fsprog source tree and hacked the following patch that adds ocfs2 support.
In the
probe_ocfs()function, buf contains the first kbytes of data from the disk, and I just grab the label, suggested mount point, and UUID by indexing into buf.Some of the other probe functions define their super block structure in an e2fsprog header file, and then just cast buf to their own super block. Since ocfs2 structures are considerably more complex, I just went with the offset method.
This code would totally break if ocfs2 changes the layout of the first kbyte on disk. Are there any plans to change this?
Would anyone have a problem with me submitting this to the e2fsprogs project?
--rustyhome/rusty/probe.c renamed from probe.c +22
-0@@ -312,6 +312,27 @@return 1 ; } +static int probe_ocfs(int fd __BLKID_ATTR((unused)), + blkid_cache cache __BLKID_ATTR((unused)), + blkid_dev dev, + struct blkid_magic *id __BLKID_ATTR((unused)), + unsigned char *buf) +{ +char *label =0 ; +char *mount_point =0 ; + +if (strlen ((char *) (buf +0x230 ))) + label = (char *) (buf +0x230 ); +blkid_set_tag (dev,"LABEL" , label,64 ); + +if (strlen ((char *) (buf +0x88 ))) + mount_point = (char *) (buf +0x88 ); +blkid_set_tag (dev,"MOUNT" , mount_point,128 ); + +set_uuid (dev, (char *)(buf +0x272 )); +return 0 ; +} +/* * BLKID_BLK_OFFS is at least as large as the highest bim_kboff defined * in the type_array table below + bim_kbalign. @@ -371,6 +392,7 @@ { "swap", 0, 0x1ff6, 10, "SWAPSPACE2", 0 }, { "swap", 0, 0x3ff6, 10, "SWAP-SPACE", 0 }, { "swap", 0, 0x3ff6, 10, "SWAPSPACE2", 0 }, + { "ocfs2", 0, 8, 9, "OracleCFS", probe_ocfs }, { NULL, 0, 0, 0, NULL, NULL } };_______________________________________________
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PATCH 1/1 ocfs2 support for blkid utility
In reply to Rusty LynchQuoted 11 lines · Rusty Lynch
So... I downloaded the e2fsprog source tree and hacked the following patch that adds ocfs2 support.
In the
probe_ocfs()function, buf contains the first kbytes of data from the disk, and I just grab the label, suggested mount point, and UUID by indexing into buf.Some of the other probe functions define their super block structure in an e2fsprog header file, and then just cast buf to their own super block. Since ocfs2 structures are considerably more complex, I just went with the offset method.
It'd be cleaner to declare a couple structs in probe.h and use then in probe.c, similar to what I did for mount in:
http://oss.oracle.com/projects/ocfs/src/trunk/patches/mountocfslabel.diff
Using offsets directly is rather cryptic.
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This code would totally break if ocfs2 changes the layout of the first kbyte on disk. Are there any plans to change this?
No changes are planned, since one goal is to maintain on-disk compatibility with ocfs1 as much as possible.
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Would anyone have a problem with me submitting this to the e2fsprogs project?
Fine by me, if you take my suggestion above. ;)
-Manish