| Message ID | 1437368369-4227-1-git-send-email-ghe@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello Andrew/Mark/Goldwyn, The doc describes OCFS2 online file check feature, which is added by the last suggestion when I submitted a few online file check code patches. Online file check patches link: https://oss.oracle.com/pipermail/ocfs2-devel/2015-June/010886.html https://oss.oracle.com/pipermail/ocfs2-devel/2015-June/010885.html https://oss.oracle.com/pipermail/ocfs2-devel/2015-June/010888.html https://oss.oracle.com/pipermail/ocfs2-devel/2015-June/010887.html https://oss.oracle.com/pipermail/ocfs2-devel/2015-June/010889.html Thanks Gang >>> > This document will describe OCFS2 online file check feature. > OCFS2 is often used in high-availaibility systems. However, OCFS2 usually > converts the filesystem to read-only on errors. This may not be necessary, > since > turning the filesystem read-only would affect other running processes as > well, > decreasing availability. Then, a mount option (errors=continue) was > introduced, > which would return the EIO to the calling process and terminate furhter > processing so that the filesystem is not corrupted further. The filesystem > is > not converted to read-only, and the problematic file's inode number is > reported > in the kernel log. The user can try to check/fix this file via online > filecheck > feature. > > Signed-off-by: Gang He <ghe@suse.com> > --- > .../filesystems/ocfs2-online-filecheck.txt | 95 > ++++++++++++++++++++++ > 1 file changed, 95 insertions(+) > create mode 100644 Documentation/filesystems/ocfs2-online-filecheck.txt > > diff --git a/Documentation/filesystems/ocfs2-online-filecheck.txt > b/Documentation/filesystems/ocfs2-online-filecheck.txt > new file mode 100644 > index 0000000..d319237 > --- /dev/null > +++ b/Documentation/filesystems/ocfs2-online-filecheck.txt > @@ -0,0 +1,95 @@ > + OCFS2 online file check > + ----------------------- > + > +This document will describe OCFS2 online file check feature. > + > +Introduction > +============ > +OCFS2 is often used in high-availaibility systems. However, OCFS2 usually > +converts the filesystem to read-only on errors. This may not be necessary, > since > +turning the filesystem read-only would affect other running processes as > well, > +decreasing availability. Then, a mount option (errors=continue) was > introduced, > +which would return the EIO to the calling process and terminate furhter > +processing so that the filesystem is not corrupted further. The filesystem > is > +not converted to read-only, and the problematic file's inode number is > reported > +in the kernel log. The user can try to check/fix this file via online > filecheck > +feature. > + > +Scope > +===== > +This effort is to check/fix small issues which may hinder day-to-day > operations > +of a cluster filesystem by turning the filesystem read-only. The scope of > +checking/fixing is at the file level, initially for regular files and > eventually > +to all files (including system files) of the filesystem. > + > +In case of directory to file links is incorrect, the directory inode is > +reported as erroneous. > + > +This feature is not suited for extravagant checks which involve dependency > of > +other components of the filesystem, such as but not limited to, checking if > the > +bits for file blocks in the allocation has been set. In case of such an > error, > +the offline fsck should/would be recommended. > + > +Finally, such an operation/feature should not be automated lest the > filesystem > +may end up with more damage than before the repair attempt. So, this has to > +be performed using user interaction and consent. > + > +User interface > +============== > +When there are errors in the OCFS2 filesystem, they are usually accompanied > +by the inode number which caused the error. This inode number would be the > +input to check/fix the file. > + > +There is a sysfs file for each OCFS2 file system mounting: > + > + /sys/fs/ocfs2/<devname>/filecheck > + > +Here, <devname> indicates the name of OCFS2 volumn device which has been > already > +mounted. The file above would accept inode numbers. This could be used to > +communicate with kernel space, tell which file(inode number) will be > checked or > +fixed. Currently, three operations are supported, which includes checking > +inode, fixing inode and setting the size of result record history. > + > +1. If you want to know what error exactly happened to <inode> before fixing, > do > + > + # echo "CHECK <inode>" > /sys/fs/ocfs2/<devname>/filecheck > + # cat /sys/fs/ocfs2/<devname>/filecheck > + > +The output is like this: > + INO TYPE DONE ERROR > +39502 0 1 GENERATION > + > +<INO> lists the inode numbers. > +<TYPE> is what kind of operation you've done, 0 for inode check,1 for inode > fix. > +<DONE> indicates whether the operation has been finished. > +<ERROR> says what kind of errors was found. For the detailed error numbers, > +please refer to the file linux/fs/ocfs2/filecheck.h. > + > +2. If you determine to fix this inode, do > + > + # echo "FIX <inode>" > /sys/fs/ocfs2/<devname>/filecheck > + # cat /sys/fs/ocfs2/<devname>/filecheck > + > +The output is like this: > + INO TYPE DONE ERROR > +39502 1 1 SUCCESS > + > +This time, the <ERROR> column indicates whether this fix is successful or > not. > + > +3. The record cache is used to store the history of check/fix result. Its > +defalut size is 10, and can be adjust between the range of 10 ~ 100. You > can > +adjust the size like this: > + > + # echo "SET <size>" > /sys/fs/ocfs2/<devname>/filecheck > + > +Fixing stuff > +============ > +On receivng the inode, the filesystem would read the inode and the > +file metadata. In case of errors, the filesystem would fix the errors > +and report the problems it fixed in the kernel log. As a precautionary > measure, > +the inode must first be checked for errors before performing a final fix. > + > +The inode and the result history will be maintained temporarily in a > +small linked list buffer which would contain the last (N) inodes > +fixed/checked, the detailed errors which were fixed/checked are printed in > the > +kernel log. > -- > 2.1.2
diff --git a/Documentation/filesystems/ocfs2-online-filecheck.txt b/Documentation/filesystems/ocfs2-online-filecheck.txt new file mode 100644 index 0000000..d319237 --- /dev/null +++ b/Documentation/filesystems/ocfs2-online-filecheck.txt @@ -0,0 +1,95 @@ + OCFS2 online file check + ----------------------- + +This document will describe OCFS2 online file check feature. + +Introduction +============ +OCFS2 is often used in high-availaibility systems. However, OCFS2 usually +converts the filesystem to read-only on errors. This may not be necessary, since +turning the filesystem read-only would affect other running processes as well, +decreasing availability. Then, a mount option (errors=continue) was introduced, +which would return the EIO to the calling process and terminate furhter +processing so that the filesystem is not corrupted further. The filesystem is +not converted to read-only, and the problematic file's inode number is reported +in the kernel log. The user can try to check/fix this file via online filecheck +feature. + +Scope +===== +This effort is to check/fix small issues which may hinder day-to-day operations +of a cluster filesystem by turning the filesystem read-only. The scope of +checking/fixing is at the file level, initially for regular files and eventually +to all files (including system files) of the filesystem. + +In case of directory to file links is incorrect, the directory inode is +reported as erroneous. + +This feature is not suited for extravagant checks which involve dependency of +other components of the filesystem, such as but not limited to, checking if the +bits for file blocks in the allocation has been set. In case of such an error, +the offline fsck should/would be recommended. + +Finally, such an operation/feature should not be automated lest the filesystem +may end up with more damage than before the repair attempt. So, this has to +be performed using user interaction and consent. + +User interface +============== +When there are errors in the OCFS2 filesystem, they are usually accompanied +by the inode number which caused the error. This inode number would be the +input to check/fix the file. + +There is a sysfs file for each OCFS2 file system mounting: + + /sys/fs/ocfs2/<devname>/filecheck + +Here, <devname> indicates the name of OCFS2 volumn device which has been already +mounted. The file above would accept inode numbers. This could be used to +communicate with kernel space, tell which file(inode number) will be checked or +fixed. Currently, three operations are supported, which includes checking +inode, fixing inode and setting the size of result record history. + +1. If you want to know what error exactly happened to <inode> before fixing, do + + # echo "CHECK <inode>" > /sys/fs/ocfs2/<devname>/filecheck + # cat /sys/fs/ocfs2/<devname>/filecheck + +The output is like this: + INO TYPE DONE ERROR +39502 0 1 GENERATION + +<INO> lists the inode numbers. +<TYPE> is what kind of operation you've done, 0 for inode check,1 for inode fix. +<DONE> indicates whether the operation has been finished. +<ERROR> says what kind of errors was found. For the detailed error numbers, +please refer to the file linux/fs/ocfs2/filecheck.h. + +2. If you determine to fix this inode, do + + # echo "FIX <inode>" > /sys/fs/ocfs2/<devname>/filecheck + # cat /sys/fs/ocfs2/<devname>/filecheck + +The output is like this: + INO TYPE DONE ERROR +39502 1 1 SUCCESS + +This time, the <ERROR> column indicates whether this fix is successful or not. + +3. The record cache is used to store the history of check/fix result. Its +defalut size is 10, and can be adjust between the range of 10 ~ 100. You can +adjust the size like this: + + # echo "SET <size>" > /sys/fs/ocfs2/<devname>/filecheck + +Fixing stuff +============ +On receivng the inode, the filesystem would read the inode and the +file metadata. In case of errors, the filesystem would fix the errors +and report the problems it fixed in the kernel log. As a precautionary measure, +the inode must first be checked for errors before performing a final fix. + +The inode and the result history will be maintained temporarily in a +small linked list buffer which would contain the last (N) inodes +fixed/checked, the detailed errors which were fixed/checked are printed in the +kernel log.
This document will describe OCFS2 online file check feature. OCFS2 is often used in high-availaibility systems. However, OCFS2 usually converts the filesystem to read-only on errors. This may not be necessary, since turning the filesystem read-only would affect other running processes as well, decreasing availability. Then, a mount option (errors=continue) was introduced, which would return the EIO to the calling process and terminate furhter processing so that the filesystem is not corrupted further. The filesystem is not converted to read-only, and the problematic file's inode number is reported in the kernel log. The user can try to check/fix this file via online filecheck feature. Signed-off-by: Gang He <ghe@suse.com> --- .../filesystems/ocfs2-online-filecheck.txt | 95 ++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 Documentation/filesystems/ocfs2-online-filecheck.txt