ceph: add LAZYIO ioctl to mark a file description for lazy consistency

Allow an application to mark a file descriptor for lazy file consistency
semantics, allowing buffered reads and writes when multiple clients are
accessing the same file.

Signed-off-by: Sage Weil <sage@newdream.net>

2 files changed, 26 insertions, 0 deletions

diff --git a/fs/ceph/ioctl.c b/fs/ceph/ioctl.c
index d085f07756b4..76e307d2aba1 100644
--- a/fs/ceph/ioctl.c
+++ b/fs/ceph/ioctl.c
@@ -143,6 +143,27 @@ static long ceph_ioctl_get_dataloc(struct file *file, void __user *arg)
         return 0;
 }
 
+static long ceph_ioctl_lazyio(struct file *file)
+{
+        struct ceph_file_info *fi = file->private_data;
+        struct inode *inode = file->f_dentry->d_inode;
+        struct ceph_inode_info *ci = ceph_inode(inode);
+
+        if ((fi->fmode & CEPH_FILE_MODE_LAZY) == 0) {
+                spin_lock(&inode->i_lock);
+                ci->i_nr_by_mode[fi->fmode]--;
+                fi->fmode |= CEPH_FILE_MODE_LAZY;
+                ci->i_nr_by_mode[fi->fmode]++;
+                spin_unlock(&inode->i_lock);
+                dout("ioctl_layzio: file %p marked lazy\n", file);
+
+                ceph_check_caps(ci, 0, NULL);
+        } else {
+                dout("ioctl_layzio: file %p already lazy\n", file);
+        }
+        return 0;
+}
+
 long ceph_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
         dout("ioctl file %p cmd %u arg %lu\n", file, cmd, arg);
@@ -155,6 +176,9 @@ long ceph_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
         case CEPH_IOC_GET_DATALOC:
                 return ceph_ioctl_get_dataloc(file, (void __user *)arg);
+
+        case CEPH_IOC_LAZYIO:
+                return ceph_ioctl_lazyio(file);
         }
         return -ENOTTY;
 }
diff --git a/fs/ceph/ioctl.h b/fs/ceph/ioctl.h
index 25e4f1a9d059..88451a3b6857 100644
--- a/fs/ceph/ioctl.h
+++ b/fs/ceph/ioctl.h
@@ -37,4 +37,6 @@ struct ceph_ioctl_dataloc {
 #define CEPH_IOC_GET_DATALOC _IOWR(CEPH_IOCTL_MAGIC, 3, \
                                    struct ceph_ioctl_dataloc)
 
+#define CEPH_IOC_LAZYIO _IO(CEPH_IOCTL_MAGIC, 4)
+
 #endif