On Tue, Apr 14, 2009 at 2:20 AM, Venkatesh Srinivas <me@xxxxxxxxxxx> wrote:
> Hi,
>
> We are currently trying to trace down an NFS fault in our environment,
> where we trip the BUG() at fs/nfs/write.c:252. When we trip that bug,
> both PG_CLEAN and PG_NEED_COMMIT are set in the nfs_page's flags. That
> seems bad (from their names), but I haven't been able to find a good
> description of what the nfs_page flags mean.
>
> The flags here are the ones at include/linux/nfs_page.h:30. Do any of
> you know what they imply? Any resource that'd talk more about them?
>
> Thanks,
> -- vs
>
take a look at the context on how it is used:
in fs/nfs/write.c:
1070 static void nfs_writeback_release_full(void *calldata)
1071 {
1072 struct nfs_write_data *data = calldata;
1073 int status = data->task.tk_status;
1074
1075 /* Update attributes as result of writeback. */
1076 while (!list_empty(&data->pages)) {
<snip>
1095
1096 if (nfs_write_need_commit(data)) {
1097 memcpy(&req->wb_verf, &data->verf,
sizeof(req->wb_verf));
1098 nfs_mark_request_commit(req);
1099 nfs_end_page_writeback(page);
1100 dprintk(" marked for commit\n");
1101 goto next;
1102 }
1103 dprintk(" OK\n");
1104 remove_request:
and nfs_mark_request_commit() simply mark the page as PG_CLEAN:
415 static void
416 nfs_mark_request_commit(struct nfs_page *req)
417 {
418 struct inode *inode = req->wb_context->path.dentry->d_inode;
419 struct nfs_inode *nfsi = NFS_I(inode);
420
421 spin_lock(&inode->i_lock);
422 set_bit(PG_CLEAN, &(req)->wb_flags);
423 radix_tree_tag_set(&nfsi->nfs_page_tree,
424 req->wb_index,
425 NFS_PAGE_TAG_COMMIT);
426 spin_unlock(&inode->i_lock);
so we know that first writeback occurred, then if successful, page is
marked as clean and committed.
same goes for all other symbols.
--
Regards,
Peter Teoh
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