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authorMiklos Szeredi <miklos@szeredi.hu>2006-06-25 05:48:51 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-25 10:01:19 -0700
commitbafa96541b250a7051e3fbc5de6e8369daf8ffec (patch)
tree9b758c424fcda2d263c71f25358bb65a0abc15d4 /Documentation
parent51eb01e73599efb88c6c20b1c226d20309a75450 (diff)
[PATCH] fuse: add control filesystem
Add a control filesystem to fuse, replacing the attributes currently exported through sysfs. An empty directory '/sys/fs/fuse/connections' is still created in sysfs, and mounting the control filesystem here provides backward compatibility. Advantages of the control filesystem over the previous solution: - allows the object directory and the attributes to be owned by the filesystem owner, hence letting unpriviled users abort the filesystem connection - does not suffer from module unload race [akpm@osdl.org: fix this fs for recent dhowells depredations] [akpm@osdl.org: fix 64-bit printk warnings] Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/fuse.txt30
1 files changed, 21 insertions, 9 deletions
diff --git a/Documentation/filesystems/fuse.txt b/Documentation/filesystems/fuse.txt
index e7747774ceb..324df27704c 100644
--- a/Documentation/filesystems/fuse.txt
+++ b/Documentation/filesystems/fuse.txt
@@ -18,6 +18,14 @@ Non-privileged mount (or user mount):
user. NOTE: this is not the same as mounts allowed with the "user"
option in /etc/fstab, which is not discussed here.
+Filesystem connection:
+
+ A connection between the filesystem daemon and the kernel. The
+ connection exists until either the daemon dies, or the filesystem is
+ umounted. Note that detaching (or lazy umounting) the filesystem
+ does _not_ break the connection, in this case it will exist until
+ the last reference to the filesystem is released.
+
Mount owner:
The user who does the mounting.
@@ -86,16 +94,20 @@ Mount options
The default is infinite. Note that the size of read requests is
limited anyway to 32 pages (which is 128kbyte on i386).
-Sysfs
-~~~~~
+Control filesystem
+~~~~~~~~~~~~~~~~~~
+
+There's a control filesystem for FUSE, which can be mounted by:
-FUSE sets up the following hierarchy in sysfs:
+ mount -t fusectl none /sys/fs/fuse/connections
- /sys/fs/fuse/connections/N/
+Mounting it under the '/sys/fs/fuse/connections' directory makes it
+backwards compatible with earlier versions.
-where N is an increasing number allocated to each new connection.
+Under the fuse control filesystem each connection has a directory
+named by a unique number.
-For each connection the following attributes are defined:
+For each connection the following files exist within this directory:
'waiting'
@@ -110,7 +122,7 @@ For each connection the following attributes are defined:
connection. This means that all waiting requests will be aborted an
error returned for all aborted and new requests.
-Only a privileged user may read or write these attributes.
+Only the owner of the mount may read or write these files.
Aborting a filesystem connection
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -139,8 +151,8 @@ the filesystem. There are several ways to do this:
- Use forced umount (umount -f). Works in all cases but only if
filesystem is still attached (it hasn't been lazy unmounted)
- - Abort filesystem through the sysfs interface. Most powerful
- method, always works.
+ - Abort filesystem through the FUSE control filesystem. Most
+ powerful method, always works.
How do non-privileged mounts work?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~