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author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-14 17:35:56 -0400 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-14 17:35:56 -0400 |
commit | 33f1de69312432baecb997a570b7d77c4d02d1ed (patch) | |
tree | 24e9e7487ec3b892e120409aa2ac1b1263794373 /Documentation | |
parent | 041d6d0be82bed7e0b87181dba5d10b8ab14afd9 (diff) | |
parent | 86d006365610fe6cda243d89b67d5047dca44656 (diff) |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw:
GFS2: Whitespace fixes
GFS2: Remove unused sysfs file
GFS2: Be extra careful about deallocating inodes
GFS2: Remove no_formal_ino generating code
GFS2: Rename eattr.[ch] as xattr.[ch]
GFS2: Clean up of extended attribute support
GFS2: Add explanation of extended attr on-disk format
GFS2: Add "-o errors=panic|withdraw" mount options
GFS2: jumping to wrong label?
GFS2: free disk inode which is deleted by remote node -V2
GFS2: Add a document explaining GFS2's uevents
GFS2: Add sysfs link to device
GFS2: Replace assertion with proper error handling
GFS2: Improve error handling in inode allocation
GFS2: Add some more info to uevents
GFS2: Add online uevent to GFS2
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/filesystems/gfs2-uevents.txt | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/Documentation/filesystems/gfs2-uevents.txt b/Documentation/filesystems/gfs2-uevents.txt new file mode 100644 index 000000000000..fd966dc9979a --- /dev/null +++ b/Documentation/filesystems/gfs2-uevents.txt | |||
@@ -0,0 +1,100 @@ | |||
1 | uevents and GFS2 | ||
2 | ================== | ||
3 | |||
4 | During the lifetime of a GFS2 mount, a number of uevents are generated. | ||
5 | This document explains what the events are and what they are used | ||
6 | for (by gfs_controld in gfs2-utils). | ||
7 | |||
8 | A list of GFS2 uevents | ||
9 | ----------------------- | ||
10 | |||
11 | 1. ADD | ||
12 | |||
13 | The ADD event occurs at mount time. It will always be the first | ||
14 | uevent generated by the newly created filesystem. If the mount | ||
15 | is successful, an ONLINE uevent will follow. If it is not successful | ||
16 | then a REMOVE uevent will follow. | ||
17 | |||
18 | The ADD uevent has two environment variables: SPECTATOR=[0|1] | ||
19 | and RDONLY=[0|1] that specify the spectator status (a read-only mount | ||
20 | with no journal assigned), and read-only (with journal assigned) status | ||
21 | of the filesystem respectively. | ||
22 | |||
23 | 2. ONLINE | ||
24 | |||
25 | The ONLINE uevent is generated after a successful mount or remount. It | ||
26 | has the same environment variables as the ADD uevent. The ONLINE | ||
27 | uevent, along with the two environment variables for spectator and | ||
28 | RDONLY are a relatively recent addition (2.6.32-rc+) and will not | ||
29 | be generated by older kernels. | ||
30 | |||
31 | 3. CHANGE | ||
32 | |||
33 | The CHANGE uevent is used in two places. One is when reporting the | ||
34 | successful mount of the filesystem by the first node (FIRSTMOUNT=Done). | ||
35 | This is used as a signal by gfs_controld that it is then ok for other | ||
36 | nodes in the cluster to mount the filesystem. | ||
37 | |||
38 | The other CHANGE uevent is used to inform of the completion | ||
39 | of journal recovery for one of the filesystems journals. It has | ||
40 | two environment variables, JID= which specifies the journal id which | ||
41 | has just been recovered, and RECOVERY=[Done|Failed] to indicate the | ||
42 | success (or otherwise) of the operation. These uevents are generated | ||
43 | for every journal recovered, whether it is during the initial mount | ||
44 | process or as the result of gfs_controld requesting a specific journal | ||
45 | recovery via the /sys/fs/gfs2/<fsname>/lock_module/recovery file. | ||
46 | |||
47 | Because the CHANGE uevent was used (in early versions of gfs_controld) | ||
48 | without checking the environment variables to discover the state, we | ||
49 | cannot add any more functions to it without running the risk of | ||
50 | someone using an older version of the user tools and breaking their | ||
51 | cluster. For this reason the ONLINE uevent was used when adding a new | ||
52 | uevent for a successful mount or remount. | ||
53 | |||
54 | 4. OFFLINE | ||
55 | |||
56 | The OFFLINE uevent is only generated due to filesystem errors and is used | ||
57 | as part of the "withdraw" mechanism. Currently this doesn't give any | ||
58 | information about what the error is, which is something that needs to | ||
59 | be fixed. | ||
60 | |||
61 | 5. REMOVE | ||
62 | |||
63 | The REMOVE uevent is generated at the end of an unsuccessful mount | ||
64 | or at the end of a umount of the filesystem. All REMOVE uevents will | ||
65 | have been preceeded by at least an ADD uevent for the same fileystem, | ||
66 | and unlike the other uevents is generated automatically by the kernel's | ||
67 | kobject subsystem. | ||
68 | |||
69 | |||
70 | Information common to all GFS2 uevents (uevent environment variables) | ||
71 | ---------------------------------------------------------------------- | ||
72 | |||
73 | 1. LOCKTABLE= | ||
74 | |||
75 | The LOCKTABLE is a string, as supplied on the mount command | ||
76 | line (locktable=) or via fstab. It is used as a filesystem label | ||
77 | as well as providing the information for a lock_dlm mount to be | ||
78 | able to join the cluster. | ||
79 | |||
80 | 2. LOCKPROTO= | ||
81 | |||
82 | The LOCKPROTO is a string, and its value depends on what is set | ||
83 | on the mount command line, or via fstab. It will be either | ||
84 | lock_nolock or lock_dlm. In the future other lock managers | ||
85 | may be supported. | ||
86 | |||
87 | 3. JOURNALID= | ||
88 | |||
89 | If a journal is in use by the filesystem (journals are not | ||
90 | assigned for spectator mounts) then this will give the | ||
91 | numeric journal id in all GFS2 uevents. | ||
92 | |||
93 | 4. UUID= | ||
94 | |||
95 | With recent versions of gfs2-utils, mkfs.gfs2 writes a UUID | ||
96 | into the filesystem superblock. If it exists, this will | ||
97 | be included in every uevent relating to the filesystem. | ||
98 | |||
99 | |||
100 | |||