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authorJohn W. Linville <linville@tuxdriver.com>2012-02-15 16:24:37 -0500
committerJohn W. Linville <linville@tuxdriver.com>2012-02-15 16:24:37 -0500
commitca994a36f585432458ead9133fcfe05440edbb7b (patch)
treebe05512153a9cd5cbe1f1234bc09fd9cd388ec58 /Documentation/filesystems
parent12325280dfeba18164f9c47e226a40ab34e23ee7 (diff)
parent2504a6423b9ab4c36df78227055995644de19edb (diff)
downloadlinux-ca994a36f585432458ead9133fcfe05440edbb7b.tar.bz2
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless
Conflicts: net/mac80211/debugfs_sta.c net/mac80211/sta_info.h
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/ceph.txt18
-rw-r--r--Documentation/filesystems/nfs/00-INDEX2
-rw-r--r--Documentation/filesystems/nfs/fault_injection.txt69
-rw-r--r--Documentation/filesystems/squashfs.txt6
4 files changed, 87 insertions, 8 deletions
diff --git a/Documentation/filesystems/ceph.txt b/Documentation/filesystems/ceph.txt
index 763d8ebbbebd..d6030aa33376 100644
--- a/Documentation/filesystems/ceph.txt
+++ b/Documentation/filesystems/ceph.txt
@@ -119,12 +119,20 @@ Mount Options
must rely on TCP's error correction to detect data corruption
in the data payload.
- noasyncreaddir
- Disable client's use its local cache to satisfy readdir
- requests. (This does not change correctness; the client uses
- cached metadata only when a lease or capability ensures it is
- valid.)
+ dcache
+ Use the dcache contents to perform negative lookups and
+ readdir when the client has the entire directory contents in
+ its cache. (This does not change correctness; the client uses
+ cached metadata only when a lease or capability ensures it is
+ valid.)
+
+ nodcache
+ Do not use the dcache as above. This avoids a significant amount of
+ complex code, sacrificing performance without affecting correctness,
+ and is useful for tracking down bugs.
+ noasyncreaddir
+ Do not use the dcache as above for readdir.
More Information
================
diff --git a/Documentation/filesystems/nfs/00-INDEX b/Documentation/filesystems/nfs/00-INDEX
index a57e12411d2a..1716874a651e 100644
--- a/Documentation/filesystems/nfs/00-INDEX
+++ b/Documentation/filesystems/nfs/00-INDEX
@@ -2,6 +2,8 @@
- this file (nfs-related documentation).
Exporting
- explanation of how to make filesystems exportable.
+fault_injection.txt
+ - information for using fault injection on the server
knfsd-stats.txt
- statistics which the NFS server makes available to user space.
nfs.txt
diff --git a/Documentation/filesystems/nfs/fault_injection.txt b/Documentation/filesystems/nfs/fault_injection.txt
new file mode 100644
index 000000000000..426d166089a3
--- /dev/null
+++ b/Documentation/filesystems/nfs/fault_injection.txt
@@ -0,0 +1,69 @@
+
+Fault Injection
+===============
+Fault injection is a method for forcing errors that may not normally occur, or
+may be difficult to reproduce. Forcing these errors in a controlled environment
+can help the developer find and fix bugs before their code is shipped in a
+production system. Injecting an error on the Linux NFS server will allow us to
+observe how the client reacts and if it manages to recover its state correctly.
+
+NFSD_FAULT_INJECTION must be selected when configuring the kernel to use this
+feature.
+
+
+Using Fault Injection
+=====================
+On the client, mount the fault injection server through NFS v4.0+ and do some
+work over NFS (open files, take locks, ...).
+
+On the server, mount the debugfs filesystem to <debug_dir> and ls
+<debug_dir>/nfsd. This will show a list of files that will be used for
+injecting faults on the NFS server. As root, write a number n to the file
+corresponding to the action you want the server to take. The server will then
+process the first n items it finds. So if you want to forget 5 locks, echo '5'
+to <debug_dir>/nfsd/forget_locks. A value of 0 will tell the server to forget
+all corresponding items. A log message will be created containing the number
+of items forgotten (check dmesg).
+
+Go back to work on the client and check if the client recovered from the error
+correctly.
+
+
+Available Faults
+================
+forget_clients:
+ The NFS server keeps a list of clients that have placed a mount call. If
+ this list is cleared, the server will have no knowledge of who the client
+ is, forcing the client to reauthenticate with the server.
+
+forget_openowners:
+ The NFS server keeps a list of what files are currently opened and who
+ they were opened by. Clearing this list will force the client to reopen
+ its files.
+
+forget_locks:
+ The NFS server keeps a list of what files are currently locked in the VFS.
+ Clearing this list will force the client to reclaim its locks (files are
+ unlocked through the VFS as they are cleared from this list).
+
+forget_delegations:
+ A delegation is used to assure the client that a file, or part of a file,
+ has not changed since the delegation was awarded. Clearing this list will
+ force the client to reaquire its delegation before accessing the file
+ again.
+
+recall_delegations:
+ Delegations can be recalled by the server when another client attempts to
+ access a file. This test will notify the client that its delegation has
+ been revoked, forcing the client to reaquire the delegation before using
+ the file again.
+
+
+tools/nfs/inject_faults.sh script
+=================================
+This script has been created to ease the fault injection process. This script
+will detect the mounted debugfs directory and write to the files located there
+based on the arguments passed by the user. For example, running
+`inject_faults.sh forget_locks 1` as root will instruct the server to forget
+one lock. Running `inject_faults forget_locks` will instruct the server to
+forgetall locks.
diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt
index 7db3ebda5a4c..403c090aca39 100644
--- a/Documentation/filesystems/squashfs.txt
+++ b/Documentation/filesystems/squashfs.txt
@@ -93,8 +93,8 @@ byte alignment:
Compressed data blocks are written to the filesystem as files are read from
the source directory, and checked for duplicates. Once all file data has been
-written the completed inode, directory, fragment, export and uid/gid lookup
-tables are written.
+written the completed inode, directory, fragment, export, uid/gid lookup and
+xattr tables are written.
3.1 Compression options
-----------------------
@@ -151,7 +151,7 @@ in each metadata block. Directories are sorted in alphabetical order,
and at lookup the index is scanned linearly looking for the first filename
alphabetically larger than the filename being looked up. At this point the
location of the metadata block the filename is in has been found.
-The general idea of the index is ensure only one metadata block needs to be
+The general idea of the index is to ensure only one metadata block needs to be
decompressed to do a lookup irrespective of the length of the directory.
This scheme has the advantage that it doesn't require extra memory overhead
and doesn't require much extra storage on disk.