Re: Compatibility issue with 2.2.19pre7

From: Trond Myklebust (trond.myklebust@fys.uio.no)
Date: Thu Jan 11 2001 - 12:44:04 EST


>>>>> " " == Manfred Spraul <manfred@colorfullife.com> writes:

> Trond Myklebust wrote:
>>
>>
>> As for the issue of casting 'fh->data' as a 'struct knfsd' then
>> that is a perfectly valid operation.
>>
> No it isn't.

> fh-> data is an array of characters, thus without any alignment
> restrictions. 'struct knfsd' begins with a pointer, thus it
> must be 4 or 8 byte aligned.

> The portable 'struct nfs_fh' structure would be

> #define NFS_HANDLESIZE 64
> struct nfs_fh {
> unsigned short len; void* data[NFS_HANDLESIZE/sizeof(void*)];
> };

Ok. I see your point now. How about the appended patch then? It means
an extra copy operation, but it should be a lot less ugly than doing
manual alignment...

Cheers,
  Trond

diff -u --recursive --new-file linux-2.2.18/fs/lockd/svcsubs.c linux-2.2.18-fix_ppc/fs/lockd/svcsubs.c
--- linux-2.2.18/fs/lockd/svcsubs.c Mon Dec 11 01:49:44 2000
+++ linux-2.2.18-fix_ppc/fs/lockd/svcsubs.c Thu Jan 11 18:43:31 2001
@@ -49,34 +49,37 @@
 nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
                                         struct nfs_fh *f)
 {
- struct knfs_fh *fh = (struct knfs_fh *) f->data;
+ struct knfs_fh fh;
         struct nlm_file *file;
         unsigned int hash;
         u32 nfserr;
 
+ /* Copy filehandle to avoid pointer alignment issues */
+ memcpy(&fh, f->data, sizeof(fh));
+
         dprintk("lockd: nlm_file_lookup(%s/%u)\n",
- kdevname(u32_to_kdev_t(fh->fh_dev)), fh->fh_ino);
+ kdevname(u32_to_kdev_t(fh.fh_dev)), fh.fh_ino);
 
- hash = file_hash(u32_to_kdev_t(fh->fh_dev), u32_to_ino_t(fh->fh_ino));
+ hash = file_hash(u32_to_kdev_t(fh.fh_dev), u32_to_ino_t(fh.fh_ino));
 
         /* Lock file table */
         down(&nlm_file_sema);
 
         for (file = nlm_files[hash]; file; file = file->f_next) {
- if (file->f_handle.fh_dcookie == fh->fh_dcookie &&
- !memcmp(&file->f_handle, fh, sizeof(*fh)))
+ if (file->f_handle.fh_dcookie == fh.fh_dcookie &&
+ !memcmp(&file->f_handle, &fh, sizeof(fh)))
                         goto found;
         }
 
         dprintk("lockd: creating file for %s/%u\n",
- kdevname(u32_to_kdev_t(fh->fh_dev)), fh->fh_ino);
+ kdevname(u32_to_kdev_t(fh.fh_dev)), fh.fh_ino);
         nfserr = nlm4_lck_denied_nolocks;
         file = (struct nlm_file *) kmalloc(sizeof(*file), GFP_KERNEL);
         if (!file)
                 goto out_unlock;
 
         memset(file, 0, sizeof(*file));
- file->f_handle = *fh;
+ memcpy(&file->f_handle, &fh, sizeof(file->f_handle));
         file->f_sema = MUTEX;
 
         /* Open the file. Note that this must not sleep for too long, else
@@ -85,7 +88,7 @@
          * We have to make sure we have the right credential to open
          * the file.
          */
- if ((nfserr = nlmsvc_ops->fopen(rqstp, fh, &file->f_file)) != 0) {
+ if ((nfserr = nlmsvc_ops->fopen(rqstp, &fh, &file->f_file)) != 0) {
                 dprintk("lockd: open failed (nfserr %d)\n", ntohl(nfserr));
                 goto out_free;
         }
-
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This archive was generated by hypermail 2b29 : Mon Jan 15 2001 - 21:00:31 EST