afs: Fix updating of i_blocks on file/dir extension

When an afs file or directory is modified locally such that the total file
size is extended, i_blocks needs to be recalculated too.

Fix this by making afs_write_end() and afs_edit_dir_add() call
afs_set_i_size() rather than setting inode->i_size directly as that also
recalculates inode->i_blocks.

This can be tested by creating and writing into directories and files and
then examining them with du.  Without this change, directories show a 4
blocks (they start out at 2048 bytes) and files show 0 blocks; with this
change, they should show a number of blocks proportional to the file size
rounded up to 1024.

Fixes: 31143d5d ("AFS: implement basic file write support")
Fixes: 63a4681f ("afs: Locally edit directory data for mkdir/create/unlink/...")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/163113612442.352844.11162345591911691150.stgit@warthog.procyon.org.uk/

fs/afs/dir_edit.c

@@ -263,7 +263,7 @@ void afs_edit_dir_add(struct afs_vnode *vnode,
 		if (b == nr_blocks) {
 			_debug("init %u", b);
 			afs_edit_init_block(meta, block, b);
-			i_size_write(&vnode->vfs_inode, (b + 1) * AFS_DIR_BLOCK_SIZE);
+			afs_set_i_size(vnode, (b + 1) * AFS_DIR_BLOCK_SIZE);
 		}
 
 		/* Only lower dir pages have a counter in the header. */
@@ -296,7 +296,7 @@ void afs_edit_dir_add(struct afs_vnode *vnode,
 new_directory:
 	afs_edit_init_block(meta, meta, 0);
 	i_size = AFS_DIR_BLOCK_SIZE;
-	i_size_write(&vnode->vfs_inode, i_size);
+	afs_set_i_size(vnode, i_size);
 	slot = AFS_DIR_RESV_BLOCKS0;
 	page = page0;
 	block = meta;

fs/afs/inode.c

@@ -53,16 +53,6 @@ static noinline void dump_vnode(struct afs_vnode *vnode, struct afs_vnode *paren
 		dump_stack();
 }
 
-/*
- * Set the file size and block count.  Estimate the number of 512 bytes blocks
- * used, rounded up to nearest 1K for consistency with other AFS clients.
- */
-static void afs_set_i_size(struct afs_vnode *vnode, u64 size)
-{
-	i_size_write(&vnode->vfs_inode, size);
-	vnode->vfs_inode.i_blocks = ((size + 1023) >> 10) << 1;
-}
-
 /*
  * Initialise an inode from the vnode status.
  */

fs/afs/internal.h

@@ -1596,6 +1596,16 @@ static inline void afs_update_dentry_version(struct afs_operation *op,
 			(void *)(unsigned long)dir_vp->scb.status.data_version;
 }
 
+/*
+ * Set the file size and block count.  Estimate the number of 512 bytes blocks
+ * used, rounded up to nearest 1K for consistency with other AFS clients.
+ */
+static inline void afs_set_i_size(struct afs_vnode *vnode, u64 size)
+{
+	i_size_write(&vnode->vfs_inode, size);
+	vnode->vfs_inode.i_blocks = ((size + 1023) >> 10) << 1;
+}
+
 /*
  * Check for a conflicting operation on a directory that we just unlinked from.
  * If someone managed to sneak a link or an unlink in on the file we just

fs/afs/write.c

@@ -137,7 +137,7 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 		write_seqlock(&vnode->cb_lock);
 		i_size = i_size_read(&vnode->vfs_inode);
 		if (maybe_i_size > i_size)
-			i_size_write(&vnode->vfs_inode, maybe_i_size);
+			afs_set_i_size(vnode, maybe_i_size);
 		write_sequnlock(&vnode->cb_lock);
 	}