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Commit 71d0a611 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix an unstable write data integrity race 



Commit 2c61be0a (NFS: Ensure that the WRITE
and COMMIT RPC calls are always uninterruptible) exposed a race on file
close. In order to ensure correct close-to-open behaviour, we want to wait
for all outstanding background commit operations to complete.

This patch adds an inode flag that indicates if a commit operation is under
way, and provides a mechanism to allow ->write_inode() to wait for its
completion if this is a data integrity flush.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent cdd29ecf

fs/nfs/write.c

+32 −4
Original line number Diff line number Diff line
@@ -1201,6 +1201,25 @@ int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data) 




#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)

static int nfs_commit_set_lock(struct nfs_inode *nfsi, int may_wait)

{

	if (!test_and_set_bit(NFS_INO_COMMIT, &nfsi->flags))

		return 1;

	if (may_wait && !out_of_line_wait_on_bit_lock(&nfsi->flags,

				NFS_INO_COMMIT, nfs_wait_bit_killable,

				TASK_KILLABLE))

		return 1;

	return 0;

}



static void nfs_commit_clear_lock(struct nfs_inode *nfsi)

{

	clear_bit(NFS_INO_COMMIT, &nfsi->flags);

	smp_mb__after_clear_bit();

	wake_up_bit(&nfsi->flags, NFS_INO_COMMIT);

}





static void nfs_commitdata_release(void *data)

{

	struct nfs_write_data *wdata = data;
@@ -1262,8 +1281,6 @@ static int nfs_commit_rpcsetup(struct list_head *head, 
	task = rpc_run_task(&task_setup_data);

	if (IS_ERR(task))

		return PTR_ERR(task);

	if (how & FLUSH_SYNC)

		rpc_wait_for_completion_task(task);

	rpc_put_task(task);

	return 0;

}
@@ -1294,6 +1311,7 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how) 
				BDI_RECLAIMABLE);

		nfs_clear_page_tag_locked(req);

	}

	nfs_commit_clear_lock(NFS_I(inode));

	return -ENOMEM;

}
@@ -1349,6 +1367,7 @@ static void nfs_commit_release(void *calldata) 
	next:

		nfs_clear_page_tag_locked(req);

	}

	nfs_commit_clear_lock(NFS_I(data->inode));

	nfs_commitdata_release(calldata);

}
@@ -1363,8 +1382,11 @@ static const struct rpc_call_ops nfs_commit_ops = { 
static int nfs_commit_inode(struct inode *inode, int how)

{

	LIST_HEAD(head);

	int res;

	int may_wait = how & FLUSH_SYNC;

	int res = 0;



	if (!nfs_commit_set_lock(NFS_I(inode), may_wait))

		goto out;

	spin_lock(&inode->i_lock);

	res = nfs_scan_commit(inode, &head, 0, 0);

	spin_unlock(&inode->i_lock);
@@ -1372,7 +1394,13 @@ static int nfs_commit_inode(struct inode *inode, int how) 
		int error = nfs_commit_list(inode, &head, how);

		if (error < 0)

			return error;

	}

		if (may_wait)

			wait_on_bit(&NFS_I(inode)->flags, NFS_INO_COMMIT,

					nfs_wait_bit_killable,

					TASK_KILLABLE);

	} else

		nfs_commit_clear_lock(NFS_I(inode));

out:

	return res;

}

include/linux/nfs_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -209,6 +209,7 @@ struct nfs_inode { 
#define NFS_INO_FLUSHING	(4)		/* inode is flushing out data */

#define NFS_INO_FSCACHE		(5)		/* inode can be cached by FS-Cache */

#define NFS_INO_FSCACHE_LOCK	(6)		/* FS-Cache cookie management lock */

#define NFS_INO_COMMIT		(7)		/* inode is committing unstable writes */



static inline struct nfs_inode *NFS_I(const struct inode *inode)

{