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authorWeston Andros Adamson <dros@primarydata.com>2014-11-12 20:08:00 +0300
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-11-25 01:00:42 +0300
commitcb1410c71e0b6b2eba8c1890645a76ff86169d24 (patch)
tree22fb6770fed66df7d51676e25e5a525bdd352abe /fs/nfs/write.c
parent6a74c0c9402b85647793da70edc9d6b097d54472 (diff)
downloadlinux-cb1410c71e0b6b2eba8c1890645a76ff86169d24.tar.xz
NFS: fix subtle change in COMMIT behavior
Recent work in the pgio layer made it possible for there to be more than one request per page. This caused a subtle change in commit behavior, because write.c:nfs_commit_unstable_pages compares the number of *pages* waiting for writeback against the number of requests on a commit list to choose when to send a COMMIT in a non-blocking flush. This is probably hard to hit in normal operation - you have to be using rsize/wsize < PAGE_SIZE, or pnfs with lots of boundaries that are not page aligned to have a noticeable change in behavior. Signed-off-by: Weston Andros Adamson <dros@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs/nfs/write.c')
-rw-r--r--fs/nfs/write.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index f83b02dc9166..d489ff3f438f 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -670,7 +670,8 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
nfs_lock_request(req);
spin_lock(&inode->i_lock);
- if (!nfsi->npages && NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
+ if (!nfsi->nrequests &&
+ NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
inode->i_version++;
/*
* Swap-space should not get truncated. Hence no need to plug the race
@@ -681,9 +682,11 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
SetPagePrivate(req->wb_page);
set_page_private(req->wb_page, (unsigned long)req);
}
- nfsi->npages++;
+ nfsi->nrequests++;
/* this a head request for a page group - mark it as having an
- * extra reference so sub groups can follow suit */
+ * extra reference so sub groups can follow suit.
+ * This flag also informs pgio layer when to bump nrequests when
+ * adding subrequests. */
WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
kref_get(&req->wb_kref);
spin_unlock(&inode->i_lock);
@@ -709,7 +712,11 @@ static void nfs_inode_remove_request(struct nfs_page *req)
wake_up_page(head->wb_page, PG_private);
clear_bit(PG_MAPPED, &head->wb_flags);
}
- nfsi->npages--;
+ nfsi->nrequests--;
+ spin_unlock(&inode->i_lock);
+ } else {
+ spin_lock(&inode->i_lock);
+ nfsi->nrequests--;
spin_unlock(&inode->i_lock);
}
@@ -1735,7 +1742,7 @@ static int nfs_commit_unstable_pages(struct inode *inode, struct writeback_contr
/* Don't commit yet if this is a non-blocking flush and there
* are a lot of outstanding writes for this mapping.
*/
- if (nfsi->commit_info.ncommit <= (nfsi->npages >> 1))
+ if (nfsi->commit_info.ncommit <= (nfsi->nrequests >> 1))
goto out_mark_dirty;
/* don't wait for the COMMIT response */