aboutsummaryrefslogtreecommitdiff
path: root/Documentation/filesystems
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/Locking24
-rw-r--r--Documentation/filesystems/caching/cachefiles.txt8
-rw-r--r--Documentation/filesystems/pohmelfs/design_notes.txt5
-rw-r--r--Documentation/filesystems/pohmelfs/info.txt21
-rw-r--r--Documentation/filesystems/vfs.txt3
5 files changed, 41 insertions, 20 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 76efe5b71d7..3120f8dd2c3 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -512,16 +512,24 @@ locking rules:
BKL mmap_sem PageLocked(page)
open: no yes
close: no yes
-fault: no yes
-page_mkwrite: no yes no
+fault: no yes can return with page locked
+page_mkwrite: no yes can return with page locked
access: no yes
- ->page_mkwrite() is called when a previously read-only page is
-about to become writeable. The file system is responsible for
-protecting against truncate races. Once appropriate action has been
-taking to lock out truncate, the page range should be verified to be
-within i_size. The page mapping should also be checked that it is not
-NULL.
+ ->fault() is called when a previously not present pte is about
+to be faulted in. The filesystem must find and return the page associated
+with the passed in "pgoff" in the vm_fault structure. If it is possible that
+the page may be truncated and/or invalidated, then the filesystem must lock
+the page, then ensure it is not already truncated (the page lock will block
+subsequent truncate), and then return with VM_FAULT_LOCKED, and the page
+locked. The VM will unlock the page.
+
+ ->page_mkwrite() is called when a previously read-only pte is
+about to become writeable. The filesystem again must ensure that there are
+no truncate/invalidate races, and then return with the page locked. If
+the page has been truncated, the filesystem should not look up a new page
+like the ->fault() handler, but simply return with VM_FAULT_NOPAGE, which
+will cause the VM to retry the fault.
->access() is called when get_user_pages() fails in
acces_process_vm(), typically used to debug a process through
diff --git a/Documentation/filesystems/caching/cachefiles.txt b/Documentation/filesystems/caching/cachefiles.txt
index c78a49b7bba..748a1ae49e1 100644
--- a/Documentation/filesystems/caching/cachefiles.txt
+++ b/Documentation/filesystems/caching/cachefiles.txt
@@ -407,7 +407,7 @@ A NOTE ON SECURITY
==================
CacheFiles makes use of the split security in the task_struct. It allocates
-its own task_security structure, and redirects current->act_as to point to it
+its own task_security structure, and redirects current->cred to point to it
when it acts on behalf of another process, in that process's context.
The reason it does this is that it calls vfs_mkdir() and suchlike rather than
@@ -429,9 +429,9 @@ This means it may lose signals or ptrace events for example, and affects what
the process looks like in /proc.
So CacheFiles makes use of a logical split in the security between the
-objective security (task->sec) and the subjective security (task->act_as). The
-objective security holds the intrinsic security properties of a process and is
-never overridden. This is what appears in /proc, and is what is used when a
+objective security (task->real_cred) and the subjective security (task->cred).
+The objective security holds the intrinsic security properties of a process and
+is never overridden. This is what appears in /proc, and is what is used when a
process is the target of an operation by some other process (SIGKILL for
example).
diff --git a/Documentation/filesystems/pohmelfs/design_notes.txt b/Documentation/filesystems/pohmelfs/design_notes.txt
index 6d6db60d567..dcf83358716 100644
--- a/Documentation/filesystems/pohmelfs/design_notes.txt
+++ b/Documentation/filesystems/pohmelfs/design_notes.txt
@@ -56,9 +56,10 @@ workloads and can fully utilize the bandwidth to the servers when doing bulk
data transfers.
POHMELFS clients operate with a working set of servers and are capable of balancing read-only
-operations (like lookups or directory listings) between them.
+operations (like lookups or directory listings) between them according to IO priorities.
Administrators can add or remove servers from the set at run-time via special commands (described
-in Documentation/pohmelfs/info.txt file). Writes are replicated to all servers.
+in Documentation/pohmelfs/info.txt file). Writes are replicated to all servers, which are connected
+with write permission turned on. IO priority and permissions can be changed in run-time.
POHMELFS is capable of full data channel encryption and/or strong crypto hashing.
One can select any kernel supported cipher, encryption mode, hash type and operation mode
diff --git a/Documentation/filesystems/pohmelfs/info.txt b/Documentation/filesystems/pohmelfs/info.txt
index 4e3d5015708..db2e4139362 100644
--- a/Documentation/filesystems/pohmelfs/info.txt
+++ b/Documentation/filesystems/pohmelfs/info.txt
@@ -1,6 +1,8 @@
POHMELFS usage information.
-Mount options:
+Mount options.
+All but index, number of crypto threads and maximum IO size can changed via remount.
+
idx=%u
Each mountpoint is associated with a special index via this option.
Administrator can add or remove servers from the given index, so all mounts,
@@ -52,16 +54,27 @@ mcache_timeout=%u
Usage examples.
-Add (or remove if it already exists) server server1.net:1025 into the working set with index $idx
+Add server server1.net:1025 into the working set with index $idx
with appropriate hash algorithm and key file and cipher algorithm, mode and key file:
-$cfg -a server1.net -p 1025 -i $idx -K $hash_key -k $cipher_key
+$cfg A add -a server1.net -p 1025 -i $idx -K $hash_key -k $cipher_key
Mount filesystem with given index $idx to /mnt mountpoint.
Client will connect to all servers specified in the working set via previous command:
mount -t pohmel -o idx=$idx q /mnt
-One can add or remove servers from working set after mounting too.
+Change permissions to read-only (-I 1 option, '-I 2' - write-only, 3 - rw):
+$cfg A modify -a server1.net -p 1025 -i $idx -I 1
+
+Change IO priority to 123 (node with the highest priority gets read requests).
+$cfg A modify -a server1.net -p 1025 -i $idx -P 123
+One can check currect status of all connections in the mountstats file:
+# cat /proc/$PID/mountstats
+...
+device none mounted on /mnt with fstype pohmel
+idx addr(:port) socket_type protocol active priority permissions
+0 server1.net:1026 1 6 1 250 1
+0 server2.net:1025 1 6 1 123 3
Server installation.
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index deeeed0faa8..f49eecf2e57 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -277,8 +277,7 @@ or bottom half).
unfreeze_fs: called when VFS is unlocking a filesystem and making it writable
again.
- statfs: called when the VFS needs to get filesystem statistics. This
- is called with the kernel lock held
+ statfs: called when the VFS needs to get filesystem statistics.
remount_fs: called when the filesystem is remounted. This is called
with the kernel lock held