We cannot set a .checkpoint op in simple_dir_operations because they get
used mostly for pseudo-filesystem interfaces. Those provide a userspace
interface to special kernel data structures which are difficult or
impossible to checkpoint reliably for some uses of checkpoint/restart.
Specifically they may be unreliable when migrating a checkpoint to a
different machine or even across boots of the same machine with the same
kernel.
However mounts of ramfs are capable of reliably supporting checkpoint/restart
because they can be backed-up from userspace. So we add a new set of dir
operations based on simple_dir_operations but which support checkpoint.
Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
---
fs/ramfs/inode.c | 19 ++++++++++++++++++-
fs/ramfs/internal.h | 1 -
2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index c948534..62d26c5 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -44,6 +44,23 @@
static const struct super_operations ramfs_ops;
static const struct inode_operations ramfs_dir_inode_operations;
+#ifdef CONFIG_CHECKPOINT
+static const struct file_operations ramfs_dir_operations = {
+ /* Just like simple_dir_operations except... */
+ .open = dcache_dir_open,
+ .release = dcache_dir_close,
+ .llseek = dcache_dir_lseek,
+ .read = generic_read_dir,
+ .readdir = dcache_readdir,
+ .fsync = simple_sync_file,
+
+ /* The checkpoint ops are unlike simple_dir_operations */
+ .checkpoint = generic_file_checkpoint,
+};
+#else
+#define ramfs_dir_operations simple_dir_operations
+#endif
+
static struct backing_dev_info ramfs_backing_dev_info = {
.name = "ramfs",
.ra_pages = 0, /* No readahead */
@@ -75,7 +92,7 @@ struct inode *ramfs_get_inode(struct super_block *sb, int mode, dev_t dev)
break;
case S_IFDIR:
inode->i_op = &ramfs_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
+ inode->i_fop = &ramfs_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
diff --git a/fs/ramfs/internal.h b/fs/ramfs/internal.h
index 6b33063..9a11302 100644
--- a/fs/ramfs/internal.h
+++ b/fs/ramfs/internal.h
@@ -9,6 +9,5 @@
* 2 of the License, or (at your option) any later version.
*/
-
extern const struct address_space_operations ramfs_aops;
extern const struct inode_operations ramfs_file_inode_operations;
--
1.6.3.3
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