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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: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
J. Bruce Fields 2009-06-15 16:03:53 -07:00
parent 9d2a3f31d6
commit d911df7b8d
1 changed files with 39 additions and 30 deletions
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69
fs/nfsd/vfs.c
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@ -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)