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Commit b8413f98 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix a hang/infinite loop in nfs_wb_page() 



When one of the two waits in nfs_commit_inode() is interrupted, it
returns a non-negative value, which causes nfs_wb_page() to think
that the operation was successful causing it to busy-loop rather
than exiting.
It also causes nfs_file_fsync() to incorrectly report the file as
being successfully committed to disk.

This patch fixes both problems by ensuring that we return an error
if the attempts to wait fail.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
parent b31268ac

fs/nfs/write.c

+19 −12
Original line number Diff line number Diff line
@@ -1261,13 +1261,17 @@ void 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)

{

	int ret;



	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;

	if (!may_wait)

		return 0;

	ret = out_of_line_wait_on_bit_lock(&nfsi->flags,

				NFS_INO_COMMIT,

				nfs_wait_bit_killable,

				TASK_KILLABLE);

	return (ret < 0) ? ret : 1;

}



static void nfs_commit_clear_lock(struct nfs_inode *nfsi)
@@ -1443,9 +1447,10 @@ int nfs_commit_inode(struct inode *inode, int how) 
{

	LIST_HEAD(head);

	int may_wait = how & FLUSH_SYNC;

	int res = 0;

	int res;



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

	res = nfs_commit_set_lock(NFS_I(inode), may_wait);

	if (res <= 0)

		goto out_mark_dirty;

	spin_lock(&inode->i_lock);

	res = nfs_scan_commit(inode, &head, 0, 0);
@@ -1454,12 +1459,14 @@ 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,

		if (!may_wait)

			goto out_mark_dirty;

		error = wait_on_bit(&NFS_I(inode)->flags,

				NFS_INO_COMMIT,

				nfs_wait_bit_killable,

				TASK_KILLABLE);

		else

			goto out_mark_dirty;

		if (error < 0)

			return error;

	} else

		nfs_commit_clear_lock(NFS_I(inode));

	return res;