| Message ID | 1403792592-1517-1-git-send-email-avi@cloudius-systems.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/26/2014 05:23 PM, Avi Kivity wrote: > XDR requires 4-byte alignment; nfs4d READLINK reply writes out the padding, > but truncates the packet to the padding-less size. > > Fix by taking the padding into consideration when truncating the packet. > Ping. I should have mentioned that without this, readlink() returns an I/O error on the client. > Signed-off-by: Avi Kivity <avi@cloudius-systems.com> > --- > fs/nfsd/nfs4xdr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 83baf2b..cba93ea 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -3267,7 +3267,7 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd > > wire_count = htonl(maxcount); > write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4); > - xdr_truncate_encode(xdr, length_offset + 4 + maxcount); > + xdr_truncate_encode(xdr, length_offset + 4 + ALIGN(maxcount, 4)); > if (maxcount & 3) > write_bytes_to_xdr_buf(xdr->buf, length_offset + 4 + maxcount, > &zero, 4 - (maxcount&3)); -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 7/1/2014 19:21, Avi Kivity wrote: > On 06/26/2014 05:23 PM, Avi Kivity wrote: >> XDR requires 4-byte alignment; nfs4d READLINK reply writes out the padding, >> but truncates the packet to the padding-less size. >> >> Fix by taking the padding into consideration when truncating the packet. >> > > Ping. I should have mentioned that without this, readlink() returns an I/O error on the client. Yes, I got [root@localhost ~]# ll /mnt/ ls: cannot read symbolic link /mnt/test: Input/output error total 4 -rw-r--r--. 1 root root 0 Jun 14 01:21 123456 lrwxrwxrwx. 1 root root 6 Jul 2 03:33 test drwxr-xr-x. 1 root root 0 Jul 2 23:50 tmp drwxr-xr-x. 1 root root 60 Jul 2 23:44 tree [root@localhost ~]# It's introduced by commit 476a7b1f4b2c (nfsd4: don't treat readlink like a zero-copy operation). > >> Signed-off-by: Avi Kivity <avi@cloudius-systems.com> >> --- >> fs/nfsd/nfs4xdr.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c >> index 83baf2b..cba93ea 100644 >> --- a/fs/nfsd/nfs4xdr.c >> +++ b/fs/nfsd/nfs4xdr.c >> @@ -3267,7 +3267,7 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd >> wire_count = htonl(maxcount); >> write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4); >> - xdr_truncate_encode(xdr, length_offset + 4 + maxcount); >> + xdr_truncate_encode(xdr, length_offset + 4 + ALIGN(maxcount, 4)); NFSD uses (XDR_QUADLEN(maxcount) << 2)) usually. Anyway, it's a nice fix. Reviewed-by: Kinglong Mee <kinglongmee@gmail.com> thanks, Kinglong Mee -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Jul 02, 2014 at 04:40:15PM +0800, Kinglong Mee wrote: > > On 7/1/2014 19:21, Avi Kivity wrote: > > On 06/26/2014 05:23 PM, Avi Kivity wrote: > >> XDR requires 4-byte alignment; nfs4d READLINK reply writes out the padding, > >> but truncates the packet to the padding-less size. > >> > >> Fix by taking the padding into consideration when truncating the packet. > >> > > > > Ping. I should have mentioned that without this, readlink() returns an I/O error on the client. Thanks, queueing up for 3.16. > Yes, I got > [root@localhost ~]# ll /mnt/ > ls: cannot read symbolic link /mnt/test: Input/output error > total 4 > -rw-r--r--. 1 root root 0 Jun 14 01:21 123456 > lrwxrwxrwx. 1 root root 6 Jul 2 03:33 test > drwxr-xr-x. 1 root root 0 Jul 2 23:50 tmp > drwxr-xr-x. 1 root root 60 Jul 2 23:44 tree > [root@localhost ~]# > > It's introduced by commit 476a7b1f4b2c (nfsd4: don't treat readlink like a zero-copy operation). ... > >> + xdr_truncate_encode(xdr, length_offset + 4 + ALIGN(maxcount, 4)); > > NFSD uses (XDR_QUADLEN(maxcount) << 2)) usually. Eh, I didn't know about ALIGN()--I think I prefer it. > Anyway, it's a nice fix. > > Reviewed-by: Kinglong Mee <kinglongmee@gmail.com> Thanks! I've also added your symptoms and the problematic commit to the changelog. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 83baf2b..cba93ea 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3267,7 +3267,7 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd wire_count = htonl(maxcount); write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4); - xdr_truncate_encode(xdr, length_offset + 4 + maxcount); + xdr_truncate_encode(xdr, length_offset + 4 + ALIGN(maxcount, 4)); if (maxcount & 3) write_bytes_to_xdr_buf(xdr->buf, length_offset + 4 + maxcount, &zero, 4 - (maxcount&3));
XDR requires 4-byte alignment; nfs4d READLINK reply writes out the padding, but truncates the packet to the padding-less size. Fix by taking the padding into consideration when truncating the packet. Signed-off-by: Avi Kivity <avi@cloudius-systems.com> --- fs/nfsd/nfs4xdr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)