Re: [PATCH 1/3] Introduce btrfs_iget helper

David Woodhouse
2008-08-13T09:41:30Z

On Wed, 2008-08-13 at 10:07 +0100, David Woodhouse wrote:
> /* the inode and parent dir are two different roots */
> if (new && root != sub_root) {
> igrab(inode);
> sub_root->inode = inode;
> do_orphan = 1;
> }

Hmmmm.... looking at that, don't we need to store the _parent_ root
object ID in the file handle too, if it can be different from the child?

Something like this, perhaps. Given that I think we've already given up
on exporting by NFSv2, do we care about another 8 bytes in the fh size?

diff --git a/export.c b/export.c
index 34e4631..1b8875c 100644
--- a/export.c
+++ b/export.c
@@ -8,12 +8,14 @@
#include "compat.h"

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
-#define FILEID_BTRFS_WITHOUT_PARENT 0x4e
-#define FILEID_BTRFS_WITH_PARENT 0x4f
+#define FILEID_BTRFS_WITHOUT_PARENT 0x4d
+#define FILEID_BTRFS_WITH_PARENT 0x4e
+#define FILEID_BTRFS_WITH_PARENT_ROOT 0x4f
#endif

#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, parent_objectid)/4)
-#define BTRFS_FID_SIZE_CONNECTABLE (sizeof(struct btrfs_fid)/4)
+#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, parent_root_objectid)/4)
+#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid)/4)

static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
int connectable)
@@ -36,16 +38,25 @@ static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,

if (connectable && !S_ISDIR(inode->i_mode)) {
struct inode *parent;
+ u64 parent_root_id;

spin_lock(&dentry->d_lock);

parent = dentry->d_parent->d_inode;
fid->parent_objectid = BTRFS_I(parent)->location.objectid;
fid->parent_gen = parent->i_generation;
+ parent_root_id = BTRFS_I(parent)->root->objectid;

spin_unlock(&dentry->d_lock);
- len = BTRFS_FID_SIZE_CONNECTABLE;
- type = FILEID_BTRFS_WITH_PARENT;
+
+ if (parent_root_id != fid->root_objectid) {
+ fid->parent_root_objectid = parent_root_id;
+ len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
+ type = FILEID_BTRFS_WITH_PARENT_ROOT;
+ } else {
+ len = BTRFS_FID_SIZE_CONNECTABLE;
+ type = FILEID_BTRFS_WITH_PARENT;
+ }
}

*max_len = len;
@@ -88,11 +99,17 @@ static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
u64 objectid, root_objectid;
u32 generation;

- if (fh_type != FILEID_BTRFS_WITH_PARENT ||
- fh_len != BTRFS_FID_SIZE_CONNECTABLE)
+ if (fh_type == FILEID_BTRFS_WITH_PARENT) {
+ if (fh_len != BTRFS_FID_SIZE_CONNECTABLE)
+ return NULL;
+ root_objectid = fid->root_objectid;
+ } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
+ if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
+ return NULL;
+ root_objectid = fid->parent_root_objectid;
+ } else
return NULL;

- root_objectid = fid->root_objectid;
objectid = fid->parent_objectid;
generation = fid->parent_gen;

@@ -108,6 +125,8 @@ static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,

if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
+ (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
+ fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
(fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
return NULL;
diff --git a/export.h b/export.h
index 019ca3a..074348a 100644
--- a/export.h
+++ b/export.h
@@ -12,6 +12,8 @@ struct btrfs_fid {

u64 parent_objectid;
u32 parent_gen;
+
+ u64 parent_root_objectid;
} __attribute__ ((packed));

#endif

--
David Woodhouse Open Source Technology Centre
David.Woodhouse@intel.com Intel Corporation