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author | David Howells <dhowells@redhat.com> | 2018-04-09 22:12:31 +0200 |
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committer | David Howells <dhowells@redhat.com> | 2018-04-09 22:12:31 +0200 |
commit | 6f8880d8e68155726a2a22e8787cfebf1ffcab08 (patch) | |
tree | b0e11598c62e9d9c01f3a41cadb7f71b1b901692 /Documentation/filesystems/afs.txt | |
parent | afs: Prospectively look up extra files when doing a single lookup (diff) | |
download | linux-6f8880d8e68155726a2a22e8787cfebf1ffcab08.tar.xz linux-6f8880d8e68155726a2a22e8787cfebf1ffcab08.zip |
afs: Implement @sys substitution handling
Implement the AFS feature by which @sys at the end of a pathname component
may be substituted for one of a list of values, typically naming the
operating system. Up to 16 alternatives may be specified and these are
tried in turn until one works. Each network namespace has[*] a separate
independent list.
Upon creation of a new network namespace, the list of values is
initialised[*] to a single OpenAFS-compatible string representing arch type
plus "_linux26". For example, on x86_64, the sysname is "amd64_linux26".
[*] Or will, once network namespace support is finalised in kAFS.
The list may be set by:
# for i in foo bar linux-x86_64; do echo $i; done >/proc/fs/afs/sysname
for which separate writes to the same fd are amalgamated and applied on
close. The LF character may be used as a separator to specify multiple
items in the same write() call.
The list may be cleared by:
# echo >/proc/fs/afs/sysname
and read by:
# cat /proc/fs/afs/sysname
foo
bar
linux-x86_64
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'Documentation/filesystems/afs.txt')
-rw-r--r-- | Documentation/filesystems/afs.txt | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/Documentation/filesystems/afs.txt b/Documentation/filesystems/afs.txt index c5254f6d234d..8c6ea7b41048 100644 --- a/Documentation/filesystems/afs.txt +++ b/Documentation/filesystems/afs.txt @@ -11,7 +11,7 @@ Contents: - Proc filesystem. - The cell database. - Security. - - Examples. + - The @sys substitution. ======== @@ -230,3 +230,29 @@ If a file is opened with a particular key and then the file descriptor is passed to a process that doesn't have that key (perhaps over an AF_UNIX socket), then the operations on the file will be made with key that was used to open the file. + + +===================== +THE @SYS SUBSTITUTION +===================== + +The list of up to 16 @sys substitutions for the current network namespace can +be configured by writing a list to /proc/fs/afs/sysname: + + [root@andromeda ~]# echo foo amd64_linux_26 >/proc/fs/afs/sysname + +or cleared entirely by writing an empty list: + + [root@andromeda ~]# echo >/proc/fs/afs/sysname + +The current list for current network namespace can be retrieved by: + + [root@andromeda ~]# cat /proc/fs/afs/sysname + foo + amd64_linux_26 + +When @sys is being substituted for, each element of the list is tried in the +order given. + +By default, the list will contain one item that conforms to the pattern +"<arch>_linux_26", amd64 being the name for x86_64. |