2013-09-02 18:17:56

by Myklebust, Trond

[permalink] [raw]
Subject: [PATCH v2] NFS: Ensure that rmdir() waits for sillyrenames to complete

If an NFS client does

mkdir("dir");
fd = open("dir/file");
unlink("dir/file");
close(fd);
rmdir("dir");

then the asynchronous nature of the sillyrename operation means that
we can end up getting EBUSY for the rmdir() in the above test. Fix
that by ensuring that we wait for any in-progress sillyrenames
before sending the rmdir() to the server.

Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/dir.c | 19 +++++++++++++------
fs/nfs/unlink.c | 7 +++++++
include/linux/nfs_fs.h | 1 +
3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index d8149e9..187caa4 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1694,12 +1694,19 @@ int nfs_rmdir(struct inode *dir, struct dentry *dentry)
dir->i_sb->s_id, dir->i_ino, dentry->d_name.name);

trace_nfs_rmdir_enter(dir, dentry);
- error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
- /* Ensure the VFS deletes this inode */
- if (error == 0 && dentry->d_inode != NULL)
- clear_nlink(dentry->d_inode);
- else if (error == -ENOENT)
- nfs_dentry_handle_enoent(dentry);
+ if (dentry->d_inode) {
+ nfs_wait_on_sillyrename(dentry);
+ error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
+ /* Ensure the VFS deletes this inode */
+ switch (error) {
+ case 0:
+ clear_nlink(dentry->d_inode);
+ break;
+ case -ENOENT:
+ nfs_dentry_handle_enoent(dentry);
+ }
+ } else
+ error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
trace_nfs_rmdir_exit(dir, dentry, error);

return error;
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 2c1485d..0c6dfe0 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -207,6 +207,13 @@ out_free:
return ret;
}

+void nfs_wait_on_sillyrename(struct dentry *dentry)
+{
+ struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
+
+ wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) == 1);
+}
+
void nfs_block_sillyrename(struct dentry *dentry)
{
struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 7125cef..3ea4cde 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -524,6 +524,7 @@ static inline void nfs4_label_free(void *label) {}
* linux/fs/nfs/unlink.c
*/
extern void nfs_complete_unlink(struct dentry *dentry, struct inode *);
+extern void nfs_wait_on_sillyrename(struct dentry *dentry);
extern void nfs_block_sillyrename(struct dentry *dentry);
extern void nfs_unblock_sillyrename(struct dentry *dentry);
extern int nfs_sillyrename(struct inode *dir, struct dentry *dentry);
--
1.8.3.1



2013-09-03 20:44:38

by William Dauchy

[permalink] [raw]
Subject: Re: [PATCH v2] NFS: Ensure that rmdir() waits for sillyrenames to complete

On Sep03 18:50, Myklebust, Trond wrote:
> Thanks again for testing! Does the following fixup on top of the 'v2'
> patch also help?
> --- a/fs/nfs/unlink.c
> +++ b/fs/nfs/unlink.c
> @@ -211,7 +211,7 @@ void nfs_wait_on_sillyrename(struct dentry *dentry)
> {
> struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
>
> - wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) == 1);
> + wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) <= 1);
> }
>
> void nfs_block_sillyrename(struct dentry *dentry)

hmmm I just realized your v2 version had `== 1`; in fact I tested your v1
with `== 0`. Let me some time to retest the v2.

Thanks,

--
William


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2013-09-04 09:19:49

by William Dauchy

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Subject: Re: [PATCH v2] NFS: Ensure that rmdir() waits for sillyrenames to complete

On Sep03 20:47, Myklebust, Trond wrote:
> On Tue, 2013-09-03 at 22:44 +0200, William Dauchy wrote:
> > On Sep03 18:50, Myklebust, Trond wrote:
> > > Thanks again for testing! Does the following fixup on top of the 'v2'
> > > patch also help?
> > > --- a/fs/nfs/unlink.c
> > > +++ b/fs/nfs/unlink.c
> > > @@ -211,7 +211,7 @@ void nfs_wait_on_sillyrename(struct dentry *dentry)
> > > {
> > > struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
> > >
> > > - wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) == 1);
> > > + wait_event(nfsi->waitqueue, atomic_read(&nfsi->silly_count) <= 1);
> > > }
> > >
> > > void nfs_block_sillyrename(struct dentry *dentry)
> >
> > hmmm I just realized your v2 version had `== 1`; in fact I tested your v1
> > with `== 0`. Let me some time to retest the v2.

After some more testing the v2 was ok with `== 1`; I tested the v1 too
fast without seeing a v2 has been resent. I guess you can revert `<= 1`

Tested-by: William Dauchy <[email protected]>

Sorry for the noise,
--
William


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2013-09-03 09:33:50

by William Dauchy

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Subject: Re: [PATCH v2] NFS: Ensure that rmdir() waits for sillyrenames to complete

On Mon, Sep 2, 2013 at 8:17 PM, Trond Myklebust
<[email protected]> wrote:
> If an NFS client does
>
> mkdir("dir");
> fd = open("dir/file");
> unlink("dir/file");
> close(fd);
> rmdir("dir");
>
> then the asynchronous nature of the sillyrename operation means that
> we can end up getting EBUSY for the rmdir() in the above test. Fix
> that by ensuring that we wait for any in-progress sillyrenames
> before sending the rmdir() to the server.

I tested the patch on top of a 3.10.x
When doing heavy operations like rm -rf dir/ with lots of data, the
process gets stuck for ever.
removing the patch fixes the issue.

--
William

2013-09-03 18:50:35

by Myklebust, Trond

[permalink] [raw]
Subject: Re: [PATCH v2] NFS: Ensure that rmdir() waits for sillyrenames to complete

On Tue, 2013-09-03 at 11:33 +0200, William Dauchy wrote:
> On Mon, Sep 2, 2013 at 8:17 PM, Trond Myklebust
> <[email protected]> wrote:
> > If an NFS client does
> >
> > mkdir("dir");
> > fd = open("dir/file");
> > unlink("dir/file");
> > close(fd);
> > rmdir("dir");
> >
> > then the asynchronous nature of the sillyrename operation means that
> > we can end up getting EBUSY for the rmdir() in the above test. Fix
> > that by ensuring that we wait for any in-progress sillyrenames
> > before sending the rmdir() to the server.
>
> I tested the patch on top of a 3.10.x
> When doing heavy operations like rm -rf dir/ with lots of data, the
> process gets stuck for ever.
> removing the patch fixes the issue.
>

Hi William,

Thanks again for testing! Does the following fixup on top of the 'v2'
patch also help?

Cheers
Trond

--
Trond Myklebust
Linux NFS client maintainer

NetApp
[email protected]
http://www.netapp.com


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2013-09-03 20:47:37

by Myklebust, Trond

[permalink] [raw]
Subject: Re: [PATCH v2] NFS: Ensure that rmdir() waits for sillyrenames to complete

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