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Commit d911df7b authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

nfsd: Pull write-gathering code out of nfsd_vfs_write 



This is a relatively self-contained piece of code that handles a special
case--move it to its own function.

Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
parent 9d2a3f31

fs/nfsd/vfs.c

+39 −30
Original line number Diff line number Diff line
@@ -963,6 +963,43 @@ static void kill_suid(struct dentry *dentry) 
	mutex_unlock(&dentry->d_inode->i_mutex);

}



/*

 * Gathered writes: If another process is currently writing to the file,

 * there's a high chance this is another nfsd (triggered by a bulk write

 * from a client's biod). Rather than syncing the file with each write

 * request, we sleep for 10 msec.

 *

 * I don't know if this roughly approximates C. Juszak's idea of

 * gathered writes, but it's a nice and simple solution (IMHO), and it

 * seems to work:-)

 *

 * Note: we do this only in the NFSv2 case, since v3 and higher have a

 * better tool (separate unstable writes and commits) for solving this

 * problem.

 */

static int wait_for_concurrent_writes(struct file *file)

{

	struct inode *inode = file->f_path.dentry->d_inode;

	static ino_t last_ino;

	static dev_t last_dev;

	int err = 0;



	if (atomic_read(&inode->i_writecount) > 1

	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {

		dprintk("nfsd: write defer %d\n", task_pid_nr(current));

		msleep(10);

		dprintk("nfsd: write resume %d\n", task_pid_nr(current));

	}



	if (inode->i_state & I_DIRTY) {

		dprintk("nfsd: write sync %d\n", task_pid_nr(current));

		err = nfsd_sync(file);

	}

	last_ino = inode->i_ino;

	last_dev = inode->i_sb->s_dev;

	return err;

}



static __be32

nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,

				loff_t offset, struct kvec *vec, int vlen,
@@ -1026,36 +1063,8 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, 
	if (host_err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID)))

		kill_suid(dentry);



	if (host_err >= 0 && stable && use_wgather) {

		static ino_t	last_ino;

		static dev_t	last_dev;



		/*

		 * Gathered writes: If another process is currently

		 * writing to the file, there's a high chance

		 * this is another nfsd (triggered by a bulk write

		 * from a client's biod). Rather than syncing the

		 * file with each write request, we sleep for 10 msec.

		 *

		 * I don't know if this roughly approximates

		 * C. Juszak's idea of gathered writes, but it's a

		 * nice and simple solution (IMHO), and it seems to

		 * work:-)

		 */

		if (atomic_read(&inode->i_writecount) > 1

		    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {

			dprintk("nfsd: write defer %d\n", task_pid_nr(current));

			msleep(10);

			dprintk("nfsd: write resume %d\n", task_pid_nr(current));

		}



		if (inode->i_state & I_DIRTY) {

			dprintk("nfsd: write sync %d\n", task_pid_nr(current));

			host_err=nfsd_sync(file);

		}

		last_ino = inode->i_ino;

		last_dev = inode->i_sb->s_dev;

	}

	if (host_err >= 0 && stable && use_wgather)

		host_err = wait_for_concurrent_writes(file);



	dprintk("nfsd: write complete host_err=%d\n", host_err);

	if (host_err >= 0)