docs: filesystems: convert ocfs2-online-filecheck.txt to ReST

- Add a SPDX header;
- Add a document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/6007166acc3252697755836354bd29b5a5fb82aa.1581955849.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 0 insertions, 94 deletions

diff --git a/Documentation/filesystems/ocfs2-online-filecheck.txt b/Documentation/filesystems/ocfs2-online-filecheck.txt
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-		    OCFS2 online file check
-		    -----------------------
-
-This document will describe OCFS2 online file check feature.
-
-Introduction
-============
-OCFS2 is often used in high-availability systems. However, OCFS2 usually
-converts the filesystem to read-only when encounters an error. 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) is introduced, which would return the
--EIO errno to the calling process and terminate further 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 directory for each OCFS2 file system mounting:
-
-  /sys/fs/ocfs2/<devname>/filecheck
-
-Here, <devname> indicates the name of OCFS2 volume 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 "<inode>" > /sys/fs/ocfs2/<devname>/filecheck/check
-  # cat /sys/fs/ocfs2/<devname>/filecheck/check
-
-The output is like this:
-  INO		DONE	ERROR
-39502		1	GENERATION
-
-<INO> lists the inode numbers.
-<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 "<inode>" > /sys/fs/ocfs2/<devname>/filecheck/fix
-  # cat /sys/fs/ocfs2/<devname>/filecheck/fix
-
-The output is like this:
-  INO		DONE	ERROR
-39502		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 results. It's
-default size is 10, and can be adjust between the range of 10 ~ 100. You can
-adjust the size like this:
-
-  # echo "<size>" > /sys/fs/ocfs2/<devname>/filecheck/set
-
-Fixing stuff
-============
-On receiving 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.