Oh, btw, I committed your patch. :-)
-sam
On Aug 19, 2007, at 6:31 PM, Murali Vilayannur wrote:
Sam,
immutable files are by definition to prevent users from deleting
(including admins who may make a mistake)
Once immutable file bit is set, you cannot delete the file or do
anything to it even as root!
It is a file-level lockdown.
The only way out of the lockdown is to be able to unset the bit.
You should of course be able to unset the immutable file bit
property as root.
That should be the only thing we should allow...
Hence the check should not be there in set-eattr.sm and del-eattr.sm
thanks,
Murali
Maybe I'm missing something but I think deleting the file should be
allowed, in fact it should be the only way to remove the immutable
attribute.
-sam
thanks,
Murali
-sam
On Aug 17, 2007, at 10:09 PM, Murali Vilayannur wrote:
Sam,
The problem is not in the system call (fsetxattr) but the
arguments
to it..
user.pvfs2.meta_hint is the key and val is actually a uint64
which is
a bitwise OR
of PVFS_IMMUTABLE_FL, other pvfs flags.
modify_val() in pvfs2-xattr.c will give an example of this usage.
Sorry, it is a little convoluted ..:(
but I couldn't/didn't want to do more string parsing on server
side.
Feel free to change that if you think it is needlessly convoluted.
thanks,
Murali
PS: let me know how the caching patches work out :)
I havent had too much time to play with it since Feb though.
Hope it works :)
On 8/17/07, Sam Lang <[EMAIL PROTECTED]> wrote:
Hi Murali,
I wrote a little program to test the performance of the read-
caching
immutable file stuff. With the attached program, I get a EINVAL
error on the read of the file after the immutable attribute has
been
set (using fsetxattr). Also, ls -la gives me really strange
results
for the files that I've set that immutable attribute on. In the
below listing, tmpfile1 and tmpfile10 didn't have the immutable
attribute set. It looks like the problem is with the fsetxattr
system call. The setfattr util does the same thing. When I set
the
xattr with pvfs2-xattr though, I don't see the corruption in
listing
the file. I'll try to investigate what fsetxattr is doing,
but are
you aware of any problems with using the system call?
-sam
[EMAIL PROTECTED]:/tmp/pvfsmnt# ls -la
total 10260
drwxrwxrwt 1 slang mpi 4096 2007-08-17 16:35 .
drwxrwxrwt 5 root root 4096 2007-08-17 15:47 ..
drwxrwxrwx 1 slang mpi 4096 2007-08-17 15:47 lost+found
-rw-r--r-- 1 root root 0 2007-08-17 16:24 tmpfile1
-rw-r--r-- 1 root root 10485760 2007-08-17 16:34 tmpfile10
?--------- ? ? ? ? ? tmpfile11
?--------- ? ? ? ? ? tmpfile2
?--------- ? ? ? ? ? tmpfile3
?--------- ? ? ? ? ? tmpfile4
?--------- ? ? ? ? ? tmpfile5
?--------- ? ? ? ? ? tmpfile6
?--------- ? ? ? ? ? tmpfile7
?--------- ? ? ? ? ? tmpfile9
[EMAIL PROTECTED]:/tmp/pvfsmnt#
On Feb 20, 2007, at 1:06 AM, Murali Vilayannur wrote:
Hi all,
Finally, I got some time to whip up the read-caching patches for
non-mutable files into a semblance of shape and stability.
With this patch, I am able to get I/Os to a file (marked
immutable)
serviced from the page-cache. One can tag a file as immutable by
running,
./src/apps/admin/pvfs2-xattr -s -k user.pvfs2.meta_hint -v
"+immutable" /path/to/pvfs2-file
To verify if a file is indeed tagged immutable,
./src/apps/admin/pvfs2-xattr -t -k user.pvfs2.meta_hint /path/
to/
pvfs2-file
(or)
./src/apps/admin/pvfs2-stat /path/to/pvfs2/file
I have also added some preliminary statistics exported via
/proc/sys/pvfs2/stats/
that can be used as a placeholder for more interesting
statistics
later on.
Currently, it only shows # of reads, writes, hits in thepage-
cache
and misses.
For some reason now, cache hits do not happen across a file
close.
Within a file open-close session, all reads get serviced from
the
cache though. Very weird.
My hunch is that file pages are somehow getting removed from the
radix
tree of the address space due to some page-ref counting
issues. I
will
dig into this later this week.
In any case, this code should not cause any regression of older
code
paths (hopefully!) and should not impose any performance
penalties for
workloads making use of the page-cache because of the way we
aggregate
cache miss I/Os to the server.
It was really nice to be able to make use of the iox()
infrastructure
that was already in place to service non-contigous file and
memory
I/O.
More details of the implementation is described in the thread
below.
http://www.beowulf-underground.org/pipermail/pvfs2-developers/
2006-
November/002847.html
Hopefully, I have addressed most of Pete's comments.
More comments and testing welcome!
thanks,
Murali
<read-cache-5.patch>
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