Messages in this thread Patch in this message | | | From | "Doug Nazar" <> | Subject | RE: 2.6.28-rc3 truncates nfsd results | Date | Wed, 5 Nov 2008 06:16:28 -0500 |
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> From: J. Bruce Fields [mailto:bfields@fieldses.org] > On Tue, Nov 04, 2008 at 01:27:23PM -0500, Doug Nazar wrote: > > Commit 8d7c4203 "nfsd: fix failure to set eof in readdir in some situations" > > breaks the nfsd server. Bisected it back to this commit and reverting it > > fixes the problem. > > > > However, it only happens on certain machines even with the same kernel & > > filesystem (ext3). I've two groups of similar computers, each group running > > identical kernels. The ones listing only ~250 files are of course in error. > > Eldritch is running 2.6.28-rc3 with that commit reverted. With 2.8.28-rc3 it > > showed the incorrect number. > > Well, that's strange; it must be staring me in the face, but I don't see > the problem (and can't reproduce it). Can you watch for the readdir > with wireshark and see if it's returning an error on the readdir? Or is > it just returning succesfully with eof set after the first ~250 > entries?
Ok, think I've figured it out.
The computers showing the issue are not using dir_index. This causes ext3 to read a block at a time, which then means we can end up with buf.full==0 but not finished reading the directory. Before 8d7c4203, we'd always get called again because we never set nfserr_eof which papered over it.
I think the correct solution is to move nfserr_eof into the loop and remove the buf.full check so that we loop until buf.used==0. The following seems to do the right thing and reduces the network traffic since we now ensure each buffer is full.
Tested on an empty directory & large directory, eof is properly sent and no short buffers.
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 848a03e..4433c8f 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1875,11 +1875,11 @@ static int nfsd_buffered_readdir(struct file *file, filldir_t func, return -ENOMEM; offset = *offsetp; - cdp->err = nfserr_eof; /* will be cleared on successful read */ while (1) { unsigned int reclen; + cdp->err = nfserr_eof; /* will be cleared on successful read */ buf.used = 0; buf.full = 0; @@ -1912,9 +1912,6 @@ static int nfsd_buffered_readdir(struct file *file, filldir_t func, de = (struct buffered_dirent *)((char *)de + reclen); } offset = vfs_llseek(file, 0, SEEK_CUR); - cdp->err = nfserr_eof; - if (!buf.full) - break; } done:
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