Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hello Greg and Pavel, Sorry, there was a misunderstand, I was not aware that there were some design constraints for sysfs interfaces. I will review and modify this portion code. Thanks Gang >>> > On Fri, Dec 04, 2015 at 01:36:21AM -0700, Gang He wrote: >> Hi Greg, >> >> >> >>> >> > On Wed, Dec 02, 2015 at 07:05:27PM -0700, Gang He wrote: >> >> Hello Pavel, >> >> >> >> >> >> >> >> >>> >> >> > On Wed 2015-10-28 14:25:57, Gang He wrote: >> >> >> 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 fixing the file. >> >> >> One of these options could be considered: >> >> >> A file in the sys filesytem which would accept inode numbers. >> >> >> This could be used to communication back what has to be fixed or is >> >> >> fixed. >> >> >> You could write: >> >> >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck >> >> >> or >> >> >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck >> >> >> >> >> > >> >> > Are you sure this is reasonable interface? I mean sysfs is >> >> > supposed to be one value per file. And I don't think its suitable for >> >> > running commands. >> >> Usually, the corrupted file (inode) should be rarely encountered for >> >> OCFS2 >> > file system, then >> >> lots of commands are executed via this interface with high performance is >> > not expected by us. >> >> Second, after online file check is added, we also plan to add a mount > option >> > "error=fix", that means >> >> the file system can fix these errors automatically without a manual >> >> command > >> > triggering. >> > >> > It's not a "performance" issue, it's a "sysfs files only have one value" >> > type thing. Have two files, "inode_fix" and "inode_check" and then just >> > write the inode into them, no need to have a "verb " type parser. >> Current, we have three functional items "check, fix and set", in the future, > maybe we can add more item. >> Then, for each functional item, we need to create a sys file and add related > code (actual some code is duplicated), >> I prefer to one sys file to handle multiple sub-commands. > > No, sorry, that is not how sysfs works. Please use individual files, > again, sysfs is "one value per file" you should never have to write a > "parser" for a sysfs file either reading, or writing to it. > > If you need additional things in the future, great, add new sysfs files, > that makes it the easiest way for your userspace tools to be able to > determine if that feature is present in the kernel or not, it does not > have to write a command that it doesn't know if the kernel can handle or > not. > > thanks, > > greg k-h ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hi Greg, >>> > On Wed, Dec 02, 2015 at 07:05:27PM -0700, Gang He wrote: >> Hello Pavel, >> >> >> >> >>> >> > On Wed 2015-10-28 14:25:57, Gang He wrote: >> >> 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 fixing the file. >> >> One of these options could be considered: >> >> A file in the sys filesytem which would accept inode numbers. >> >> This could be used to communication back what has to be fixed or is fixed. >> >> You could write: >> >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck >> >> or >> >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck >> >> >> > >> > Are you sure this is reasonable interface? I mean sysfs is >> > supposed to be one value per file. And I don't think its suitable for >> > running commands. >> Usually, the corrupted file (inode) should be rarely encountered for OCFS2 > file system, then >> lots of commands are executed via this interface with high performance is > not expected by us. >> Second, after online file check is added, we also plan to add a mount option > "error=fix", that means >> the file system can fix these errors automatically without a manual command > triggering. > > It's not a "performance" issue, it's a "sysfs files only have one value" > type thing. Have two files, "inode_fix" and "inode_check" and then just > write the inode into them, no need to have a "verb " type parser. Current, we have three functional items "check, fix and set", in the future, maybe we can add more item. Then, for each functional item, we need to create a sys file and add related code (actual some code is duplicated), I prefer to one sys file to handle multiple sub-commands. Thanks Gang > > thanks, > > greg k-h ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
On Fri, Dec 04, 2015 at 01:36:21AM -0700, Gang He wrote: > Hi Greg, > > > >>> > > On Wed, Dec 02, 2015 at 07:05:27PM -0700, Gang He wrote: > >> Hello Pavel, > >> > >> > >> > >> >>> > >> > On Wed 2015-10-28 14:25:57, Gang He wrote: > >> >> 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 fixing the file. > >> >> One of these options could be considered: > >> >> A file in the sys filesytem which would accept inode numbers. > >> >> This could be used to communication back what has to be fixed or is > >> >> fixed. > >> >> You could write: > >> >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck > >> >> or > >> >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck > >> >> > >> > > >> > Are you sure this is reasonable interface? I mean sysfs is > >> > supposed to be one value per file. And I don't think its suitable for > >> > running commands. > >> Usually, the corrupted file (inode) should be rarely encountered for OCFS2 > > file system, then > >> lots of commands are executed via this interface with high performance is > > not expected by us. > >> Second, after online file check is added, we also plan to add a mount > >> option > > "error=fix", that means > >> the file system can fix these errors automatically without a manual > >> command > > triggering. > > > > It's not a "performance" issue, it's a "sysfs files only have one value" > > type thing. Have two files, "inode_fix" and "inode_check" and then just > > write the inode into them, no need to have a "verb " type parser. > Current, we have three functional items "check, fix and set", in the future, > maybe we can add more item. > Then, for each functional item, we need to create a sys file and add related > code (actual some code is duplicated), > I prefer to one sys file to handle multiple sub-commands. No, sorry, that is not how sysfs works. Please use individual files, again, sysfs is "one value per file" you should never have to write a "parser" for a sysfs file either reading, or writing to it. If you need additional things in the future, great, add new sysfs files, that makes it the easiest way for your userspace tools to be able to determine if that feature is present in the kernel or not, it does not have to write a command that it doesn't know if the kernel can handle or not. thanks, greg k-h ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
On Wed 2015-10-28 14:25:57, Gang He wrote: > 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 fixing the file. > One of these options could be considered: > A file in the sys filesytem which would accept inode numbers. > This could be used to communication back what has to be fixed or is fixed. > You could write: > $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck > or > $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck > Are you sure this is reasonable interface? I mean sysfs is supposed to be one value per file. And I don't think its suitable for running commands. ...or returning back results. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
On Fri 2015-12-04 01:36:21, Gang He wrote: > Hi Greg, > > > >>> > > On Wed, Dec 02, 2015 at 07:05:27PM -0700, Gang He wrote: > >> Hello Pavel, > >> > >> > >> > >> >>> > >> > On Wed 2015-10-28 14:25:57, Gang He wrote: > >> >> 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 fixing the file. > >> >> One of these options could be considered: > >> >> A file in the sys filesytem which would accept inode numbers. > >> >> This could be used to communication back what has to be fixed or is > >> >> fixed. > >> >> You could write: > >> >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck > >> >> or > >> >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck > >> >> > >> > > >> > Are you sure this is reasonable interface? I mean sysfs is > >> > supposed to be one value per file. And I don't think its suitable for > >> > running commands. > >> Usually, the corrupted file (inode) should be rarely encountered for OCFS2 > > file system, then > >> lots of commands are executed via this interface with high performance is > > not expected by us. > >> Second, after online file check is added, we also plan to add a mount > >> option > > "error=fix", that means > >> the file system can fix these errors automatically without a manual > >> command > > triggering. > > > > It's not a "performance" issue, it's a "sysfs files only have one value" > > type thing. Have two files, "inode_fix" and "inode_check" and then just > > write the inode into them, no need to have a "verb " type parser. > Current, we have three functional items "check, fix and set", in the future, > maybe we can add more item. > Then, for each functional item, we need to create a sys file and add related > code (actual some code is duplicated), > I prefer to one sys file to handle multiple sub-commands. And we prefer not to have your code in tree. Please design some reasonable interface. Abusing sysfs for this is not right. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
On Wed, Dec 02, 2015 at 07:05:27PM -0700, Gang He wrote: > Hello Pavel, > > > > >>> > > On Wed 2015-10-28 14:25:57, Gang He wrote: > >> 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 fixing the file. > >> One of these options could be considered: > >> A file in the sys filesytem which would accept inode numbers. > >> This could be used to communication back what has to be fixed or is fixed. > >> You could write: > >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck > >> or > >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck > >> > > > > Are you sure this is reasonable interface? I mean sysfs is > > supposed to be one value per file. And I don't think its suitable for > > running commands. > Usually, the corrupted file (inode) should be rarely encountered for OCFS2 > file system, then > lots of commands are executed via this interface with high performance is not > expected by us. > Second, after online file check is added, we also plan to add a mount option > "error=fix", that means > the file system can fix these errors automatically without a manual command > triggering. It's not a "performance" issue, it's a "sysfs files only have one value" type thing. Have two files, "inode_fix" and "inode_check" and then just write the inode into them, no need to have a "verb " type parser. thanks, greg k-h ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hello Pavel, >>> > On Wed 2015-10-28 14:25:57, Gang He wrote: >> 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 fixing the file. >> One of these options could be considered: >> A file in the sys filesytem which would accept inode numbers. >> This could be used to communication back what has to be fixed or is fixed. >> You could write: >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck >> or >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck >> > > Are you sure this is reasonable interface? I mean sysfs is > supposed to be one value per file. And I don't think its suitable for > running commands. Usually, the corrupted file (inode) should be rarely encountered for OCFS2 file system, then lots of commands are executed via this interface with high performance is not expected by us. Second, after online file check is added, we also plan to add a mount option "error=fix", that means the file system can fix these errors automatically without a manual command triggering. Thanks Gang > > ...or returning back results. > Pavel > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) > http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html > . ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hi Gang, thanks for pointing to explanation of the feature. What I am curious about is ... what were the real cases that you came across prompted this change and how this change would help in that case. Thanks, --Srini On 10/28/2015 09:44 PM, Gang He wrote: > Hello Srini, > > There is a doc about ocfs2 online file check. > > 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. So,the filesystem > is > not converted to read-only, and the problematic file's inode number is > reported > in the kernel log so that 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//filecheck > > Here, 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 before fixing, > do > ># echo "CHECK " > /sys/fs/ocfs2//filecheck ># cat /sys/fs/ocfs2//filecheck > > The output is like this: >INOTYPEDONEERROR > 39502 0 1 GENERATION > > lists the inode numbers. > is what kind of operation you've done, 0 for inode check,1 for inode > fix. > indicates whether the operation has been finished. > says what kind of errors was found. For the details, please refer to > the > file linux/fs/ocfs2/filecheck.h. > > 2. If you determine to fix this inode, do > ># echo "FIX " > /sys/fs/ocfs2//filecheck ># cat /sys/fs/ocfs2//filecheck > > The output is like this: >INOTYPEDONEERROR > 39502 1 1 SUCCESS > > This time, the 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 " > /sys/fs/ocfs2//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 fix history will be maintained temporarily in a > small linked list buffer which would contain the last (N) inodes > fixed/checked, along with the logs of what errors were reported/fixed. > > Thanks > Gang > > >> Hi Gang, >> >> thank you for implementing this. I would like to understand this better >> on where and how it helps ... would you mind sharing couple >> examples(real scenarios). >> >> Thanks, >> --Srini >> >> >> On 10/27/2015 11:25 PM, Gang He wrote: >>> 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 fixing the file. >>> One of
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hello Srini, The real cases are that we try to fix some independent issues without turning the file system off-line (error=continue was introduced). You know, the online file check feature is used for fixing some independent or light meta-data block corruption, e.g. inode block, file extent block, dir entry block, etc. These corruptions are usually like checksum error, blk number inconsistency, etc. Thanks Gang -- >>> > Hi Gang, > > thanks for pointing to explanation of the feature. > > What I am curious about is ... what were the real cases that you came > across prompted this change and how this change would help in that case. > > Thanks, > --Srini > > > On 10/28/2015 09:44 PM, Gang He wrote: >> Hello Srini, >> >> There is a doc about ocfs2 online file check. >> >> 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. So,the > filesystem is >> not converted to read-only, and the problematic file's inode number is > reported >> in the kernel log so that 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//filecheck >> >> Here, 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 before fixing, > do >> >># echo "CHECK " > /sys/fs/ocfs2//filecheck >># cat /sys/fs/ocfs2//filecheck >> >> The output is like this: >>INO TYPEDONEERROR >> 395020 1 GENERATION >> >> lists the inode numbers. >> is what kind of operation you've done, 0 for inode check,1 for inode > fix. >>indicates whether the operation has been finished. >> says what kind of errors was found. For the details, please refer to > the >> file linux/fs/ocfs2/filecheck.h. >> >> 2. If you determine to fix this inode, do >> >># echo "FIX " > /sys/fs/ocfs2//filecheck >># cat /sys/fs/ocfs2//filecheck >> >> The output is like this: >>INO TYPEDONEERROR >> 395021 1 SUCCESS >> >> This time, the 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 " > /sys/fs/ocfs2//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 fix history will be maintained temporarily in a >> small linked list buffer which
[Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
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 fixing the file. One of these options could be considered: A file in the sys filesytem which would accept inode numbers. This could be used to communication back what has to be fixed or is fixed. You could write: $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck or $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck Compare with first version, I use strncasecmp instead of double strncmp functions. Second, update the source file contribution vendor. Gang He (4): ocfs2: export ocfs2_kset for online file check ocfs2: sysfile interfaces for online file check ocfs2: create/remove sysfile for online file check ocfs2: check/fix inode block for online file check fs/ocfs2/Makefile | 3 +- fs/ocfs2/filecheck.c | 566 + fs/ocfs2/filecheck.h | 48 + fs/ocfs2/inode.c | 196 - fs/ocfs2/inode.h | 3 + fs/ocfs2/ocfs2_trace.h | 2 + fs/ocfs2/stackglue.c | 3 +- fs/ocfs2/stackglue.h | 2 + fs/ocfs2/super.c | 5 + 9 files changed, 820 insertions(+), 8 deletions(-) create mode 100644 fs/ocfs2/filecheck.c create mode 100644 fs/ocfs2/filecheck.h -- 2.1.2 ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hi Gang, thank you for implementing this. I would like to understand this better on where and how it helps ... would you mind sharing couple examples(real scenarios). Thanks, --Srini On 10/27/2015 11:25 PM, Gang He wrote: > 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 fixing the file. > One of these options could be considered: > A file in the sys filesytem which would accept inode numbers. > This could be used to communication back what has to be fixed or is fixed. > You could write: > $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck > or > $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck > > Compare with first version, I use strncasecmp instead of double strncmp > functions. Second, update the source file contribution vendor. > > Gang He (4): >ocfs2: export ocfs2_kset for online file check >ocfs2: sysfile interfaces for online file check >ocfs2: create/remove sysfile for online file check >ocfs2: check/fix inode block for online file check > > fs/ocfs2/Makefile | 3 +- > fs/ocfs2/filecheck.c | 566 > + > fs/ocfs2/filecheck.h | 48 + > fs/ocfs2/inode.c | 196 - > fs/ocfs2/inode.h | 3 + > fs/ocfs2/ocfs2_trace.h | 2 + > fs/ocfs2/stackglue.c | 3 +- > fs/ocfs2/stackglue.h | 2 + > fs/ocfs2/super.c | 5 + > 9 files changed, 820 insertions(+), 8 deletions(-) > create mode 100644 fs/ocfs2/filecheck.c > create mode 100644 fs/ocfs2/filecheck.h > ___ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
Re: [Ocfs2-devel] [PATCH v2 0/4] Add online file check feature
Hello Srini, There is a doc about ocfs2 online file check. 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. So,the filesystem is not converted to read-only, and the problematic file's inode number is reported in the kernel log so that 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//filecheck Here, 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 before fixing, do # echo "CHECK " > /sys/fs/ocfs2//filecheck # cat /sys/fs/ocfs2//filecheck The output is like this: INO TYPEDONEERROR 39502 0 1 GENERATION lists the inode numbers. is what kind of operation you've done, 0 for inode check,1 for inode fix. indicates whether the operation has been finished. says what kind of errors was found. For the details, please refer to the file linux/fs/ocfs2/filecheck.h. 2. If you determine to fix this inode, do # echo "FIX " > /sys/fs/ocfs2//filecheck # cat /sys/fs/ocfs2//filecheck The output is like this: INO TYPEDONEERROR 39502 1 1 SUCCESS This time, the 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 " > /sys/fs/ocfs2//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 fix history will be maintained temporarily in a small linked list buffer which would contain the last (N) inodes fixed/checked, along with the logs of what errors were reported/fixed. Thanks Gang >>> > Hi Gang, > > thank you for implementing this. I would like to understand this better > on where and how it helps ... would you mind sharing couple > examples(real scenarios). > > Thanks, > --Srini > > > On 10/27/2015 11:25 PM, Gang He wrote: >> 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 fixing the file. >> One of these options could be considered: >> A file in the sys filesytem which would accept inode numbers. >> This could be used to communication back what has to be fixed or is fixed. >> You could write: >> $# echo "CHECK " > /sys/fs/ocfs2/devname/filecheck >> or >> $# echo "FIX " > /sys/fs/ocfs2/devname/filecheck >> >> Compare with first version, I use strncasecmp instead of double strncmp >> functions. Second, update the source file contribution vendor. >> >> Gang He (4): >>ocfs2: export ocfs2_kset for
