From 71d0a6112a363e703e383ae5b12c492485c39701 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Thu, 22 Apr 2010 15:35:57 -0400 Subject: NFS: Fix an unstable write data integrity race Commit 2c61be0a9478258f77b66208a0c4b1f5f8161c3c (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: Trond Myklebust --- fs/nfs/write.c | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) (limited to 'fs/nfs') diff --git a/fs/nfs/write.c b/fs/nfs/write.c index de38d63aa92..ccde2aeb3fe 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -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; } -- cgit v1.2.3-70-g09d2