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  1. 30 11月, 2007 8 次提交
  3. 29 11月, 2007 2 次提交
  5. 28 11月, 2007 8 次提交
  7. 27 11月, 2007 8 次提交
  9. 25 11月, 2007 1 次提交
  11. 21 11月, 2007 1 次提交
    • J
      [CIFS] Fix potential data corruption when writing out cached dirty pages · cea21805
      由 Jeff Layton 提交于 
      Fix RedHat bug 329431

The idea here is separate "conscious" from "unconscious" flushes.
Conscious flushes are those due to a fsync() or close(). Unconscious
ones are flushes that occur as a side effect of some other operation or
due to memory pressure.

Currently, when an error occurs during an unconscious flush (ENOSPC or
EIO), we toss out the page and don't preserve that error to report to
the user when a conscious flush occurs. If after the unconscious flush,
there are no more dirty pages for the inode, the conscious flush will
simply return success even though there were previous errors when writing
out pages. This can lead to data corruption.

The easiest way to reproduce this is to mount up a CIFS share that's
very close to being full or where the user is very close to quota. mv
a file to the share that's slightly larger than the quota allows. The
writes will all succeed (since they go to pagecache). The mv will do a
setattr to set the new file's attributes. This calls
filemap_write_and_wait,
which will return an error since all of the pages can't be written out.
Then later, when the flush and release ops occur, there are no more
dirty pages in pagecache for the file and those operations return 0. mv
then assumes that the file was written out correctly and deletes the
original.

CIFS already has a write_behind_rc variable where it stores the results
from earlier flushes, but that value is only reported in cifs_close.
Since the VFS ignores the return value from the release operation, this
isn't helpful. We should be reporting this error during the flush
operation.

This patch does the following:

1) changes cifs_fsync to use filemap_write_and_wait and cifs_flush and also
sync to check its return code. If it returns successful, they then check
the value of write_behind_rc to see if an earlier flush had reported any
errors. If so, they return that error and clear write_behind_rc.

2) sets write_behind_rc in a few other places where pages are written
out as a side effect of other operations and the code waits on them.

3) changes cifs_setattr to only call filemap_write_and_wait for
ATTR_SIZE changes.

4) makes cifs_writepages accurately distinguish between EIO and ENOSPC
errors when writing out pages.

Some simple testing indicates that the patch works as expected and that
it fixes the reproduceable known problem.
Acked-by: NDave Kleikamp <shaggy@austin.rr.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>
      cea21805
  13. 20 11月, 2007 1 次提交
  15. 18 11月, 2007 2 次提交
    • N
      kernel BUG at fs/nfs/namespace.c:108! - can be triggered by bad server · 4c1fe2f7
      由 Neil Brown 提交于 
      
Hi Trond,

I have discovered that the BUG_ON in nfs_follow_mountpoint:

	BUG_ON(IS_ROOT(dentry));

can be triggered by a misbehaving server.

What happens is the client does a lookup and discoveres that the named
directory has a different fsid, so it initiates a mount.
It then performs a GETATTR on the mounted directory and gets a
different fsid again (due to a bug in the NFS server).
This causes nfs_follow_mountpoint to be called on the newly mounted
root, which triggers the BUG_ON.

To duplicate this, have a directory which contains some mountpoints,
and export that directory with the "crossmnt" flag using nfs-utils
1.1.1 (or 1.1.0 I think)

The GETATTR on the root of the mounted filesystem will return the
information for the top exportpoint, while a lookup will return the
correct information.  This difference causes the NFS client to BUG.

I think the best way to fix this is to trap this possibility early, so
just before completing the mount in the NFS client, check that it isn't
going to use nfs_mountpoint_inode_operations.
As long as i_op will never change once set (is that true?), this
should be adequately safe.

The following patch shows a possible approach, and it works for me.
i.e. when the NFS server is misbehaving, I get ESTALE on those
mountpoints, while when the NFS server is working correctly, I get
correct behaviour on the client.

NeilBrown
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      4c1fe2f7
    • T
      NFS: Fix the ustat() regression · b09b9417
      由 Trond Myklebust 提交于 
      Since 2.6.18, the superblock sb->s_root has been a dummy dentry with a
dummy inode. This breaks ustat(), which actually uses sb->s_root in a
vfstat() call.

Fix this by making the s_root a dummy alias to the directory inode that was
used when creating the superblock.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      b09b9417
  17. 17 11月, 2007 7 次提交
  19. 15 11月, 2007 2 次提交