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  1. 21 8月, 2009 2 次提交
  3. 20 8月, 2009 3 次提交
  5. 15 8月, 2009 19 次提交
  7. 12 8月, 2009 13 次提交
  9. 11 8月, 2009 1 次提交
    • J
      ocfs2: Fix possible deadlock when extending quota file · b409d7a0
      由 Jan Kara 提交于 
      In OCFS2, allocator locks rank above transaction start. Thus we
cannot extend quota file from inside a transaction less we could
deadlock.

We solve the problem by starting transaction not already in
ocfs2_acquire_dquot() but only in ocfs2_local_read_dquot() and
ocfs2_global_read_dquot() and we allocate blocks to quota files before starting
the transaction.  In case we crash, quota files will just have a few blocks
more but that's no problem since we just use them next time we extend the
quota file.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJoel Becker <joel.becker@oracle.com>
      b409d7a0
  11. 10 8月, 2009 2 次提交
    • B
      nfs: remove superfluous BUG_ON()s · e576e05a
      由 Bartlomiej Zolnierkiewicz 提交于 
      Subject: [PATCH] nfs: remove superfluous BUG_ON()s

Remove duplicated BUG_ON()s from nfs[4]_create_server()
(we make the same checks earlier in both functions).

This takes care of the following entries from Dan's list:

fs/nfs/client.c +1078 nfs_create_server(47) warning: variable derefenced before check 'server->nfs_client'
fs/nfs/client.c +1079 nfs_create_server(48) warning: variable derefenced before check 'server->nfs_client->rpc_ops'
fs/nfs/client.c +1363 nfs4_create_server(43) warning: variable derefenced before check 'server->nfs_client'
fs/nfs/client.c +1364 nfs4_create_server(44) warning: variable derefenced before check 'server->nfs_
Reported-by: NDan Carpenter <error27@gmail.com>
Cc: corbet@lwn.net
Cc: eteo@redhat.com
Cc: Julia Lawall <julia@diku.dk>
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      e576e05a
    • P
      NFS: read-modify-write page updating · 38c73044
      由 Peter Staubach 提交于 
      Hi.

I have a proposal for possibly resolving this issue.

I believe that this situation occurs due to the way that the
Linux NFS client handles writes which modify partial pages.

The Linux NFS client handles partial page modifications by
allocating a page from the page cache, copying the data from
the user level into the page, and then keeping track of the
offset and length of the modified portions of the page.  The
page is not marked as up to date because there are portions
of the page which do not contain valid file contents.

When a read call comes in for a portion of the page, the
contents of the page must be read in the from the server.
However, since the page may already contain some modified
data, that modified data must be written to the server
before the file contents can be read back in the from server.
And, since the writing and reading can not be done atomically,
the data must be written and committed to stable storage on
the server for safety purposes.  This means either a
FILE_SYNC WRITE or a UNSTABLE WRITE followed by a COMMIT.
This has been discussed at length previously.

This algorithm could be described as modify-write-read.  It
is most efficient when the application only updates pages
and does not read them.

My proposed solution is to add a heuristic to decide whether
to do this modify-write-read algorithm or switch to a read-
modify-write algorithm when initially allocating the page
in the write system call path.  The heuristic uses the modes
that the file was opened with, the offset in the page to
read from, and the size of the region to read.

If the file was opened for reading in addition to writing
and the page would not be filled completely with data from
the user level, then read in the old contents of the page
and mark it as Uptodate before copying in the new data.  If
the page would be completely filled with data from the user
level, then there would be no reason to read in the old
contents because they would just be copied over.

This would optimize for applications which randomly access
and update portions of files.  The linkage editor for the
C compiler is an example of such a thing.

I tested the attached patch by using rpmbuild to build the
current Fedora rawhide kernel.  The kernel without the
patch generated about 269,500 WRITE requests.  The modified
kernel containing the patch generated about 261,000 WRITE
requests.  Thus, about 8,500 fewer WRITE requests were
generated.  I suspect that many of these additional
WRITE requests were probably FILE_SYNC requests to WRITE
a single page, but I didn't test this theory.

The difference between this patch and the previous one was
to remove the unneeded PageDirty() test.  I then retested to
ensure that the resulting system continued to behave as
desired.

	Thanx...

		ps
Signed-off-by: NPeter Staubach <staubach@redhat.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      38c73044