[RFC][PATCH 3/4][cr]: Checkpoint file-owner information

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

Checkpoint the file->f_owner information for an open file. This
information will be used to restore the file-owner information
when the application is restarted from the checkpoint.

The file->f_owner information is "private" to each 'struct file' i.e.
fown_struct is not an external object shared with other file structures.
So the information can directly be added to the 'ckpt_hdr_file' object.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
 fs/checkpoint.c                |   27 +++++++++++----------------
 include/linux/checkpoint_hdr.h |    5 +++++
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/fs/checkpoint.c b/fs/checkpoint.c
index e036a7a..0fa4ce8 100644
--- a/fs/checkpoint.c
+++ b/fs/checkpoint.c
@@ -168,12 +168,19 @@ int checkpoint_file_common(struct ckpt_ctx *ctx, struct file *file,
 			   struct ckpt_hdr_file *h)
 {
 	struct cred *f_cred = (struct cred *) file->f_cred;
+	struct pid *pid = file->f_owner.pid;
 
 	h->f_flags = file->f_flags;
 	h->f_mode = file->f_mode;
 	h->f_pos = file->f_pos;
 	h->f_version = file->f_version;
 
+	h->f_owner_pid = pid_nr_ns(pid, ns_of_pid(pid));
+	h->f_owner_pid_type = file->f_owner.pid_type;
+	h->f_owner_uid = file->f_owner.uid;
+	h->f_owner_euid = file->f_owner.euid;
+	h->f_owner_signum = file->f_owner.signum;
+
 	h->f_credref = checkpoint_obj(ctx, f_cred, CKPT_OBJ_CRED);
 	if (h->f_credref < 0)
 		return h->f_credref;
@@ -184,10 +191,10 @@ int checkpoint_file_common(struct ckpt_ctx *ctx, struct file *file,
 		return h->f_secref;
 	}
 
-	ckpt_debug("file %s credref %d secref %d\n",
-		file->f_dentry->d_name.name, h->f_credref, h->f_secref);
-
-	/* FIX: need also file->f_owner, etc */
+	ckpt_debug("file %s credref %d secref %d, fowner-pid %d, type %d, "
+			"fowner-signum %d\n", file->f_dentry->d_name.name,
+			h->f_credref, h->f_secref, h->f_owner_pid,
+			h->f_owner_pid_type, h->f_owner_signum);
 
 	return 0;
 }
@@ -267,7 +274,6 @@ static int checkpoint_file_desc(struct ckpt_ctx *ctx,
 	struct fdtable *fdt;
 	int objref, ret;
 	int coe = 0;	/* avoid gcc warning */
-	pid_t pid;
 
 	h = ckpt_hdr_get_type(ctx, sizeof(*h), CKPT_HDR_FILE_DESC);
 	if (!h)
@@ -302,17 +308,6 @@ static int checkpoint_file_desc(struct ckpt_ctx *ctx,
 	}
 
 	/*
-	 * TODO: Implement c/r of fowner and f_sigio.  Should be
-	 * trivial, but for now we just refuse its checkpoint
-	 */
-	pid = f_getown(file);
-	if (pid) {
-		ret = -EBUSY;
-		ckpt_err(ctx, ret, "%(T)fd %d has an owner (%d)\n", fd);
-		goto out;
-	}
-
-	/*
 	 * if seen first time, this will add 'file' to the objhash, keep
 	 * a reference to it, dump its state while at it.
 	 */
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index 790214f..44e2a0d 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -570,6 +570,11 @@ struct ckpt_hdr_file {
 	__u64 f_pos;
 	__u64 f_version;
 	__s32 f_secref;
+	__s32 f_owner_pid;
+	__u32 f_owner_pid_type;
+	__u32 f_owner_uid;
+	__u32 f_owner_euid;
+	__s32 f_owner_signum;
 } __attribute__((aligned(8)));
 
 struct ckpt_hdr_file_generic {
-- 
1.6.0.4