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| author | Chuck Lever <chuck.lever@oracle.com> | 2007-10-26 19:32:13 +0200 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2008-01-30 08:05:45 +0100 |
| commit | 28c494c5c8d425e15b7b82571e4df6d6bc34594d (patch) | |
| tree | cbd7902da8f467182b1d5faed90349329cb8d042 | |
| parent | NFS: Change sign of some loop indices in nfs4xdr.c (diff) | |
| download | linux-28c494c5c8d425e15b7b82571e4df6d6bc34594d.tar.xz linux-28c494c5c8d425e15b7b82571e4df6d6bc34594d.zip | |
NFS: Prevent nfs_getattr() hang during heavy write workloads
POSIX requires that ctime and mtime, as reported by the stat(2) call,
reflect the activity of the most recent write(2). To that end, nfs_getattr()
flushes pending dirty writes to a file before doing a GETATTR to allow the
NFS server to set the file's size, ctime, and mtime properly.
However, nfs_getattr() can be starved when a constant stream of application
writes to a file prevents nfs_wb_nocommit() from completing. This usually
results in hangs of programs doing a stat against an NFS file that is being
written. "ls -l" is a common victim of this behavior.
To prevent starvation, hold the file's i_mutex in nfs_getattr() to
freeze applications writes temporarily so the client can more quickly obtain
clean values for a file's size, mtime, and ctime.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
| -rw-r--r-- | fs/nfs/inode.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index cd0e57f3a00f..cc3a09db41a9 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -461,9 +461,18 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME; int err; - /* Flush out writes to the server in order to update c/mtime */ - if (S_ISREG(inode->i_mode)) + /* + * Flush out writes to the server in order to update c/mtime. + * + * Hold the i_mutex to suspend application writes temporarily; + * this prevents long-running writing applications from blocking + * nfs_wb_nocommit. + */ + if (S_ISREG(inode->i_mode)) { + mutex_lock(&inode->i_mutex); nfs_wb_nocommit(inode); + mutex_unlock(&inode->i_mutex); + } /* * We may force a getattr if the user cares about atime. |