Attachment 299887 Details for Bug 438423 – patch -- fall back to synchronous writes when a background write errors out

[patch] patch -- fall back to synchronous writes when a background write errors out

0001-BZ-438423-NFS-Fall-back-to-synchronous-writes-when.patch (text/plain), 6.41 KB, created by Jeff Layton on 2008-04-01 13:14:13 UTC

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Creator: Jeff Layton

Created: 2008-04-01 13:14:13 UTC

Size: 6.41 KB

patch

obsolete

>From 8e41632a29cfec789670630779c492ea53625cf7 Mon Sep 17 00:00:00 2001
>From: Jeff Layton <jlayton@redhat.com>
>Date: Tue, 1 Apr 2008 09:08:54 -0400
>Subject: [PATCH] BZ#438423: NFS: Fall back to synchronous writes when a background write errors
>
>Backported from commit 7b159fc18d417980f57aef64cab3417ee6af70f8
>
>This helps prevent huge queues of background writes from building up
>whenever the server runs out of disk or quota space, or if someone changes
>the file access modes behind our backs.
>
>Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
>Backported-by: Jeff Layton <jlayton@redhat.com>
>---
> fs/nfs/file.c          |   64 +++++++++++++++++++++++++++++++++---------------
> fs/nfs/inode.c         |    1 +
> fs/nfs/write.c         |   15 +++++++++--
> include/linux/nfs_fs.h |    3 ++
> 4 files changed, 60 insertions(+), 23 deletions(-)
>
>diff --git a/fs/nfs/file.c b/fs/nfs/file.c
>index d949d4a..426ae9f 100644
>--- a/fs/nfs/file.c
>+++ b/fs/nfs/file.c
>@@ -169,6 +169,31 @@ static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
> }
> 
> /*
>+ * Helper for nfs_file_flush() and nfs_fsync()
>+ *
>+ * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
>+ * disk, but it retrieves and clears ctx->error after synching, despite
>+ * the two being set at the same time in nfs_context_set_write_error().
>+ * This is because the former is used to notify the _next_ call to
>+ * nfs_file_write() that a write error occured, and hence cause it to
>+ * fall back to doing a synchronous write.
>+ */
>+static int nfs_do_fsync(struct nfs_open_context *ctx, struct inode *inode)
>+{
>+	int have_error, status;
>+	int ret = 0;
>+
>+	have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
>+	status = nfs_wb_all(inode);
>+	have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
>+	if (have_error)
>+		ret = xchg(&ctx->error, 0);
>+	if (!ret)
>+		ret = status;
>+	return ret;
>+}
>+
>+/*
>  * Flush all dirty pages, and check for write errors.
>  *
>  */
>@@ -184,16 +209,11 @@ nfs_file_flush(struct file *file, fl_owner_t id)
> 	if ((file->f_mode & FMODE_WRITE) == 0)
> 		return 0;
> 	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
>-	lock_kernel();
>+
> 	/* Ensure that data+attribute caches are up to date after close() */
>-	status = nfs_wb_all(inode);
>-	if (!status) {
>-		status = ctx->error;
>-		ctx->error = 0;
>-		if (!status)
>-			nfs_revalidate_inode(NFS_SERVER(inode), inode);
>-	}
>-	unlock_kernel();
>+	status = nfs_do_fsync(ctx, inode);
>+	if (!status)
>+		nfs_revalidate_inode(NFS_SERVER(inode), inode);
> 	return status;
> }
> 
>@@ -268,19 +288,11 @@ nfs_fsync(struct file *file, struct dentry *dentry, int datasync)
> {
> 	struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
> 	struct inode *inode = dentry->d_inode;
>-	int status;
> 
> 	dfprintk(VFS, "nfs: fsync(%s/%ld)\n", inode->i_sb->s_id, inode->i_ino);
> 
> 	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
>-	lock_kernel();
>-	status = nfs_wb_all(inode);
>-	if (!status) {
>-		status = ctx->error;
>-		ctx->error = 0;
>-	}
>-	unlock_kernel();
>-	return status;
>+	return nfs_do_fsync(ctx, inode);
> }
> 
> /*
>@@ -371,6 +383,18 @@ const struct address_space_operations nfs_file_aops = {
> /* 
>  * Write to a file (through the page cache).
>  */
>+static int nfs_need_sync_write(struct file *filp, struct inode *inode)
>+{
>+	struct nfs_open_context *ctx;
>+
>+	if (IS_SYNC(inode) || (filp->f_flags & O_SYNC))
>+		return 1;
>+	ctx = filp->private_data;
>+	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
>+		return 1;
>+	return 0;
>+}
>+
> static ssize_t
> nfs_file_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t pos)
> {
>@@ -406,8 +430,8 @@ nfs_file_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t
> 	nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, count);
> 	result = generic_file_aio_write(iocb, buf, count, pos);
> 	/* Return error values for O_SYNC and IS_SYNC() */
>-	if (result >= 0 && (IS_SYNC(inode) || (iocb->ki_filp->f_flags & O_SYNC))) {
>-		int err = nfs_fsync(iocb->ki_filp, dentry, 1);
>+	if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
>+		int err = nfs_do_fsync(iocb->ki_filp->private_data, inode);
> 		if (err < 0)
> 			result = err;
> 	}
>diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
>index 612fddd..212e8ec 100644
>--- a/fs/nfs/inode.c
>+++ b/fs/nfs/inode.c
>@@ -483,6 +483,7 @@ static struct nfs_open_context *alloc_nfs_open_context(struct vfsmount *mnt, str
> 		ctx->cred = get_rpccred(cred);
> 		ctx->state = NULL;
> 		ctx->lockowner = current->files;
>+		ctx->flags = 0;
> 		ctx->error = 0;
> 		ctx->dir_cookie = 0;
> 	}
>diff --git a/fs/nfs/write.c b/fs/nfs/write.c
>index 69db0fb..31c3f23 100644
>--- a/fs/nfs/write.c
>+++ b/fs/nfs/write.c
>@@ -462,6 +462,13 @@ static void nfs_inode_remove_request(struct nfs_page *req)
> 	nfs_release_request(req);
> }
> 
>+static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
>+{
>+	ctx->error = error;
>+	smp_wmb();
>+	set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
>+}
>+
> /*
>  * Find a request
>  */
>@@ -1180,7 +1187,7 @@ static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
> 	if (task->tk_status < 0) {
> 		ClearPageUptodate(page);
> 		SetPageError(page);
>-		req->wb_context->error = task->tk_status;
>+		nfs_context_set_write_error(req->wb_context, task->tk_status);
> 		dprintk(", error = %d\n", task->tk_status);
> 	} else {
> #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
>@@ -1238,7 +1245,8 @@ static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
> 		if (task->tk_status < 0) {
> 			ClearPageUptodate(page);
> 			SetPageError(page);
>-			req->wb_context->error = task->tk_status;
>+			nfs_context_set_write_error(req->wb_context,
>+						    task->tk_status);
> 			end_page_writeback(page);
> 			nfs_inode_remove_request(req);
> 			dprintk(", error = %d\n", task->tk_status);
>@@ -1447,7 +1455,8 @@ static void nfs_commit_done(struct rpc_task *task, void *calldata)
> 			req->wb_bytes,
> 			(long long)req_offset(req));
> 		if (task->tk_status < 0) {
>-			req->wb_context->error = task->tk_status;
>+			nfs_context_set_write_error(req->wb_context,
>+						    task->tk_status);
> 			nfs_inode_remove_request(req);
> 			dprintk(", error = %d\n", task->tk_status);
> 			goto next;
>diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
>index 004e5b5..331bfff 100644
>--- a/include/linux/nfs_fs.h
>+++ b/include/linux/nfs_fs.h
>@@ -91,6 +91,9 @@ struct nfs_open_context {
> 	struct nfs4_state *state;
> 	fl_owner_t lockowner;
> 	int mode;
>+
>+	unsigned long flags;
>+#define NFS_CONTEXT_ERROR_WRITE		(0)
> 	int error;
> 
> 	struct list_head list;
>-- 
>1.5.3.6
>

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Attachments on bug 438423: 298747 | 299375 | 299887 | 302444