NFS: Allow optimisation of lseek(fd, SEEK_CUR, 0) on directories

There should be no need to grab the inode lock if we're only reading
the file offset.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2018-06-27 16:25:40 -04:00
parent 411ae722d1
commit b2b1ff3da6

View file

@ -904,23 +904,29 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
filp, offset, whence);
inode_lock(inode);
switch (whence) {
case 1:
offset += filp->f_pos;
case 0:
if (offset >= 0)
break;
default:
offset = -EINVAL;
goto out;
default:
return -EINVAL;
case SEEK_SET:
if (offset < 0)
return -EINVAL;
inode_lock(inode);
break;
case SEEK_CUR:
if (offset == 0)
return filp->f_pos;
inode_lock(inode);
offset += filp->f_pos;
if (offset < 0) {
inode_unlock(inode);
return -EINVAL;
}
}
if (offset != filp->f_pos) {
filp->f_pos = offset;
dir_ctx->dir_cookie = 0;
dir_ctx->duped = 0;
}
out:
inode_unlock(inode);
return offset;
}