Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=28c494c5c8d425e15b7b82571e4df6d6bc34594d
Commit: 28c494c5c8d425e15b7b82571e4df6d6bc34594d
Parent: 464ad6b1ade186b53a1dae863361853326b85694
Author: Chuck Lever <[EMAIL PROTECTED]>
AuthorDate: Fri Oct 26 13:32:13 2007 -0400
Committer: Trond Myklebust <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 02:05:45 2008 -0500
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 <[EMAIL PROTECTED]>
Signed-off-by: Trond Myklebust <[EMAIL PROTECTED]>
---
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 cd0e57f..cc3a09d 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.
-
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