afs: Fix application of status and callback to be under same lock

When applying the status and callback in the response of an operation,
apply them in the same critical section so that there's no race between
checking the callback state and checking status-dependent state (such as
the data version).

Fix this by:

 (1) Allocating a joint {status,callback} record (afs_status_cb) before
     calling the RPC function for each vnode for which the RPC reply
     contains a status or a status plus a callback.  A flag is set in the
     record to indicate if a callback was actually received.

 (2) These records are passed into the RPC functions to be filled in.  The
     afs_decode_status() and yfs_decode_status() functions are removed and
     the cb_lock is no longer taken.

 (3) xdr_decode_AFSFetchStatus() and xdr_decode_YFSFetchStatus() no longer
     update the vnode.

 (4) xdr_decode_AFSCallBack() and xdr_decode_YFSCallBack() no longer update
     the vnode.

 (5) vnodes, expected data-version numbers and callback break counters
     (cb_break) no longer need to be passed to the reply delivery
     functions.

     Note that, for the moment, the file locking functions still need
     access to both the call and the vnode at the same time.

 (6) afs_vnode_commit_status() is now given the cb_break value and the
     expected data_version and the task of applying the status and the
     callback to the vnode are now done here.

     This is done under a single taking of vnode->cb_lock.

 (7) afs_pages_written_back() is now called by afs_store_data() rather than
     by the reply delivery function.

     afs_pages_written_back() has been moved to before the call point and
     is now given the first and last page numbers rather than a pointer to
     the call.

 (8) The indicator from YFS.RemoveFile2 as to whether the target file
     actually got removed (status.abort_code == VNOVNODE) rather than
     merely dropping a link is now checked in afs_unlink rather than in
     xdr_decode_YFSFetchStatus().

Supplementary fixes:

 (*) afs_cache_permit() now gets the caller_access mask from the
     afs_status_cb object rather than picking it out of the vnode's status
     record.  afs_fetch_status() returns caller_access through its argument
     list for this purpose also.

 (*) afs_inode_init_from_status() now uses a write lock on cb_lock rather
     than a read lock and now sets the callback inside the same critical
     section.

Fixes: c435ee34551e ("afs: Overhaul the callback handling")
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 66 insertions, 68 deletions

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 9b44307bd934..6ed7d4df4ec6 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -116,8 +116,7 @@ struct afs_call {
 		struct afs_vlserver	*vlserver;
 	};
 	struct afs_cb_interest	*cbi;		/* Callback interest for server used */
-	struct afs_vnode	*dvnode;	/* Directory vnode of call */
-	struct afs_vnode	*xvnode;	/* Other vnode of call */
+	struct afs_vnode	*lvnode;	/* vnode being locked */
 	void			*request;	/* request data (first part) */
 	struct address_space	*mapping;	/* Pages being written from */
 	struct iov_iter		iter;		/* Buffer iterator */
@@ -134,9 +133,7 @@ struct afs_call {
 		struct afs_acl		*ret_acl;
 	};
 	struct afs_fid		*out_fid;
-	struct afs_file_status	*out_vnode_status;
-	struct afs_file_status	*out_extra_status;
-	struct afs_callback	*out_cb;
+	struct afs_status_cb	*out_dir_scb;
 	struct afs_status_cb	*out_scb;
 	struct yfs_acl		*out_yacl;
 	struct afs_volsync	*out_volsync;
@@ -155,7 +152,6 @@ struct afs_call {
 	unsigned		request_size;	/* size of request data */
 	unsigned		reply_max;	/* maximum size of reply */
 	unsigned		first_offset;	/* offset into mapping[first] */
-	unsigned int		cb_break;	/* cb_break + cb_s_break before the call */
 	union {
 		unsigned	last_to;	/* amount of mapping[last] */
 		unsigned	count2;		/* count used in unmarshalling */
@@ -180,8 +176,6 @@ struct afs_call {
 		} __attribute__((packed));
 		__be64		tmp64;
 	};
-	afs_dataversion_t	expected_version; /* Updated version expected from store */
-	afs_dataversion_t	expected_version_2; /* 2nd updated version expected from store */
 	ktime_t			reply_time;	/* Time of first reply packet */
 };
 
@@ -242,7 +236,8 @@ struct afs_read {
 	unsigned int		index;		/* Which page we're reading into */
 	unsigned int		nr_pages;
 	unsigned int		offset;		/* offset into current page */
-	void (*page_done)(struct afs_call *, struct afs_read *);
+	struct afs_vnode	*vnode;
+	void (*page_done)(struct afs_read *);
 	struct page		**pages;
 	struct page		*array[];
 };
@@ -776,6 +771,7 @@ struct afs_vl_cursor {
  * Cursor for iterating over a set of fileservers.
  */
 struct afs_fs_cursor {
+	const struct afs_call_type *type;	/* Type of call done */
 	struct afs_addr_cursor	ac;
 	struct afs_vnode	*vnode;
 	struct afs_server_list	*server_list;	/* Current server list (pins ref) */
@@ -962,30 +958,28 @@ extern int afs_flock(struct file *, int, struct file_lock *);
 /*
  * fsclient.c
  */
-#define AFS_VNODE_NOT_YET_SET	0x01
-#define AFS_VNODE_META_CHANGED	0x02
-#define AFS_VNODE_DATA_CHANGED	0x04
-extern void afs_update_inode_from_status(struct afs_vnode *, struct afs_file_status *,
-					 const afs_dataversion_t *, u8);
-
-extern int afs_fs_fetch_file_status(struct afs_fs_cursor *, struct afs_volsync *, bool);
+extern int afs_fs_fetch_file_status(struct afs_fs_cursor *, struct afs_status_cb *,
+				    struct afs_volsync *);
 extern int afs_fs_give_up_callbacks(struct afs_net *, struct afs_server *);
-extern int afs_fs_fetch_data(struct afs_fs_cursor *, struct afs_read *);
-extern int afs_fs_create(struct afs_fs_cursor *, const char *, umode_t, u64,
-			 struct afs_fid *, struct afs_file_status *, struct afs_callback *);
-extern int afs_fs_remove(struct afs_fs_cursor *, struct afs_vnode *, const char *, bool, u64);
-extern int afs_fs_link(struct afs_fs_cursor *, struct afs_vnode *, const char *, u64);
-extern int afs_fs_symlink(struct afs_fs_cursor *, const char *, const char *, u64,
-			  struct afs_fid *, struct afs_file_status *);
+extern int afs_fs_fetch_data(struct afs_fs_cursor *, struct afs_status_cb *, struct afs_read *);
+extern int afs_fs_create(struct afs_fs_cursor *, const char *, umode_t,
+			 struct afs_status_cb *, struct afs_fid *, struct afs_status_cb *);
+extern int afs_fs_remove(struct afs_fs_cursor *, struct afs_vnode *, const char *, bool,
+			 struct afs_status_cb *);
+extern int afs_fs_link(struct afs_fs_cursor *, struct afs_vnode *, const char *,
+		       struct afs_status_cb *, struct afs_status_cb *);
+extern int afs_fs_symlink(struct afs_fs_cursor *, const char *, const char *,
+			  struct afs_status_cb *, struct afs_fid *, struct afs_status_cb *);
 extern int afs_fs_rename(struct afs_fs_cursor *, const char *,
-			 struct afs_vnode *, const char *, u64, u64);
+			 struct afs_vnode *, const char *,
+			 struct afs_status_cb *, struct afs_status_cb *);
 extern int afs_fs_store_data(struct afs_fs_cursor *, struct address_space *,
-			     pgoff_t, pgoff_t, unsigned, unsigned);
-extern int afs_fs_setattr(struct afs_fs_cursor *, struct iattr *);
+			     pgoff_t, pgoff_t, unsigned, unsigned, struct afs_status_cb *);
+extern int afs_fs_setattr(struct afs_fs_cursor *, struct iattr *, struct afs_status_cb *);
 extern int afs_fs_get_volume_status(struct afs_fs_cursor *, struct afs_volume_status *);
-extern int afs_fs_set_lock(struct afs_fs_cursor *, afs_lock_type_t);
-extern int afs_fs_extend_lock(struct afs_fs_cursor *);
-extern int afs_fs_release_lock(struct afs_fs_cursor *);
+extern int afs_fs_set_lock(struct afs_fs_cursor *, afs_lock_type_t, struct afs_status_cb *);
+extern int afs_fs_extend_lock(struct afs_fs_cursor *, struct afs_status_cb *);
+extern int afs_fs_release_lock(struct afs_fs_cursor *, struct afs_status_cb *);
 extern int afs_fs_give_up_all_callbacks(struct afs_net *, struct afs_server *,
 					struct afs_addr_cursor *, struct key *);
 extern struct afs_call *afs_fs_get_capabilities(struct afs_net *, struct afs_server *,
@@ -995,16 +989,17 @@ extern int afs_fs_inline_bulk_status(struct afs_fs_cursor *, struct afs_net *,
 				     struct afs_fid *, struct afs_status_cb *,
 				     unsigned int, struct afs_volsync *);
 extern int afs_fs_fetch_status(struct afs_fs_cursor *, struct afs_net *,
-			       struct afs_fid *, struct afs_file_status *,
-			       struct afs_callback *, struct afs_volsync *);
+			       struct afs_fid *, struct afs_status_cb *,
+			       struct afs_volsync *);
 
 struct afs_acl {
 	u32	size;
 	u8	data[];
 };
 
-extern struct afs_acl *afs_fs_fetch_acl(struct afs_fs_cursor *);
-extern int afs_fs_store_acl(struct afs_fs_cursor *, const struct afs_acl *);
+extern struct afs_acl *afs_fs_fetch_acl(struct afs_fs_cursor *, struct afs_status_cb *);
+extern int afs_fs_store_acl(struct afs_fs_cursor *, const struct afs_acl *,
+			    struct afs_status_cb *);
 
 /*
  * fs_probe.c
@@ -1016,12 +1011,16 @@ extern int afs_wait_for_fs_probes(struct afs_server_list *, unsigned long);
 /*
  * inode.c
  */
-extern int afs_fetch_status(struct afs_vnode *, struct key *, bool);
+extern void afs_vnode_commit_status(struct afs_fs_cursor *,
+				    struct afs_vnode *,
+				    unsigned int,
+				    const afs_dataversion_t *,
+				    struct afs_status_cb *);
+extern int afs_fetch_status(struct afs_vnode *, struct key *, bool, afs_access_t *);
 extern int afs_iget5_test(struct inode *, void *);
 extern struct inode *afs_iget_pseudo_dir(struct super_block *, bool);
 extern struct inode *afs_iget(struct super_block *, struct key *,
-			      struct afs_fid *, struct afs_file_status *,
-			      struct afs_callback *,
+			      struct afs_fid *, struct afs_status_cb *,
 			      struct afs_cb_interest *,
 			      struct afs_vnode *);
 extern void afs_zap_data(struct afs_vnode *);
@@ -1145,6 +1144,7 @@ extern int afs_protocol_error(struct afs_call *, int, enum afs_eproto_cause);
 static inline void afs_set_fc_call(struct afs_call *call, struct afs_fs_cursor *fc)
 {
 	call->intr = fc->flags & AFS_FS_CURSOR_INTR;
+	fc->type = call->type;
 }
 
 static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t size)
@@ -1227,7 +1227,8 @@ static inline void afs_set_call_complete(struct afs_call *call,
  */
 extern void afs_put_permits(struct afs_permits *);
 extern void afs_clear_permits(struct afs_vnode *);
-extern void afs_cache_permit(struct afs_vnode *, struct key *, unsigned int);
+extern void afs_cache_permit(struct afs_vnode *, struct key *, unsigned int,
+			     struct afs_status_cb *);
 extern void afs_zap_permits(struct rcu_head *);
 extern struct key *afs_request_key(struct afs_cell *);
 extern int afs_check_permit(struct afs_vnode *, struct key *, afs_access_t *);
@@ -1353,7 +1354,6 @@ extern int afs_write_end(struct file *file, struct address_space *mapping,
 			struct page *page, void *fsdata);
 extern int afs_writepage(struct page *, struct writeback_control *);
 extern int afs_writepages(struct address_space *, struct writeback_control *);
-extern void afs_pages_written_back(struct afs_vnode *, struct afs_call *);
 extern ssize_t afs_file_write(struct kiocb *, struct iov_iter *);
 extern int afs_fsync(struct file *, loff_t, loff_t, int);
 extern vm_fault_t afs_page_mkwrite(struct vm_fault *vmf);
@@ -1369,29 +1369,33 @@ extern ssize_t afs_listxattr(struct dentry *, char *, size_t);
 /*
  * yfsclient.c
  */
-extern int yfs_fs_fetch_file_status(struct afs_fs_cursor *, struct afs_volsync *, bool);
-extern int yfs_fs_fetch_data(struct afs_fs_cursor *, struct afs_read *);
-extern int yfs_fs_create_file(struct afs_fs_cursor *, const char *, umode_t, u64,
-			      struct afs_fid *, struct afs_file_status *, struct afs_callback *);
-extern int yfs_fs_make_dir(struct afs_fs_cursor *, const char *, umode_t, u64,
-			 struct afs_fid *, struct afs_file_status *, struct afs_callback *);
-extern int yfs_fs_remove_file2(struct afs_fs_cursor *, struct afs_vnode *, const char *, u64);
-extern int yfs_fs_remove(struct afs_fs_cursor *, struct afs_vnode *, const char *, bool, u64);
-extern int yfs_fs_link(struct afs_fs_cursor *, struct afs_vnode *, const char *, u64);
-extern int yfs_fs_symlink(struct afs_fs_cursor *, const char *, const char *, u64,
-			  struct afs_fid *, struct afs_file_status *);
-extern int yfs_fs_rename(struct afs_fs_cursor *, const char *,
-			 struct afs_vnode *, const char *, u64, u64);
+extern int yfs_fs_fetch_file_status(struct afs_fs_cursor *, struct afs_status_cb *,
+				    struct afs_volsync *);
+extern int yfs_fs_fetch_data(struct afs_fs_cursor *, struct afs_status_cb *, struct afs_read *);
+extern int yfs_fs_create_file(struct afs_fs_cursor *, const char *, umode_t, struct afs_status_cb *,
+			      struct afs_fid *, struct afs_status_cb *);
+extern int yfs_fs_make_dir(struct afs_fs_cursor *, const char *, umode_t, struct afs_status_cb *,
+			   struct afs_fid *, struct afs_status_cb *);
+extern int yfs_fs_remove_file2(struct afs_fs_cursor *, struct afs_vnode *, const char *,
+			       struct afs_status_cb *, struct afs_status_cb *);
+extern int yfs_fs_remove(struct afs_fs_cursor *, struct afs_vnode *, const char *, bool,
+			 struct afs_status_cb *);
+extern int yfs_fs_link(struct afs_fs_cursor *, struct afs_vnode *, const char *,
+		       struct afs_status_cb *, struct afs_status_cb *);
+extern int yfs_fs_symlink(struct afs_fs_cursor *, const char *, const char *,
+			  struct afs_status_cb *, struct afs_fid *, struct afs_status_cb *);
+extern int yfs_fs_rename(struct afs_fs_cursor *, const char *, struct afs_vnode *, const char *,
+			 struct afs_status_cb *, struct afs_status_cb *);
 extern int yfs_fs_store_data(struct afs_fs_cursor *, struct address_space *,
-			     pgoff_t, pgoff_t, unsigned, unsigned);
-extern int yfs_fs_setattr(struct afs_fs_cursor *, struct iattr *);
+			     pgoff_t, pgoff_t, unsigned, unsigned, struct afs_status_cb *);
+extern int yfs_fs_setattr(struct afs_fs_cursor *, struct iattr *, struct afs_status_cb *);
 extern int yfs_fs_get_volume_status(struct afs_fs_cursor *, struct afs_volume_status *);
-extern int yfs_fs_set_lock(struct afs_fs_cursor *, afs_lock_type_t);
-extern int yfs_fs_extend_lock(struct afs_fs_cursor *);
-extern int yfs_fs_release_lock(struct afs_fs_cursor *);
+extern int yfs_fs_set_lock(struct afs_fs_cursor *, afs_lock_type_t, struct afs_status_cb *);
+extern int yfs_fs_extend_lock(struct afs_fs_cursor *, struct afs_status_cb *);
+extern int yfs_fs_release_lock(struct afs_fs_cursor *, struct afs_status_cb *);
 extern int yfs_fs_fetch_status(struct afs_fs_cursor *, struct afs_net *,
-			       struct afs_fid *, struct afs_file_status *,
-			       struct afs_callback *, struct afs_volsync *);
+			       struct afs_fid *, struct afs_status_cb *,
+			       struct afs_volsync *);
 extern int yfs_fs_inline_bulk_status(struct afs_fs_cursor *, struct afs_net *,
 				     struct afs_fid *, struct afs_status_cb *,
 				     unsigned int, struct afs_volsync *);
@@ -1407,8 +1411,10 @@ struct yfs_acl {
 };
 
 extern void yfs_free_opaque_acl(struct yfs_acl *);
-extern struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *, struct yfs_acl *);
-extern int yfs_fs_store_opaque_acl2(struct afs_fs_cursor *, const struct afs_acl *);
+extern struct yfs_acl *yfs_fs_fetch_opaque_acl(struct afs_fs_cursor *, struct yfs_acl *,
+					       struct afs_status_cb *);
+extern int yfs_fs_store_opaque_acl2(struct afs_fs_cursor *, const struct afs_acl *,
+				    struct afs_status_cb *);
 
 /*
  * Miscellaneous inline functions.
@@ -1423,14 +1429,6 @@ static inline struct inode *AFS_VNODE_TO_I(struct afs_vnode *vnode)
 	return &vnode->vfs_inode;
 }
 
-static inline void afs_vnode_commit_status(struct afs_fs_cursor *fc,
-					   struct afs_vnode *vnode,
-					   unsigned int cb_break)
-{
-	if (fc->ac.error == 0)
-		afs_cache_permit(vnode, fc->key, cb_break);
-}
-
 static inline void afs_check_for_remote_deletion(struct afs_fs_cursor *fc,
 						 struct afs_vnode *vnode)
 {