[XFS] cleanup pagebuf flag usage and simplify pagebuf_free.

SGI Modid: xfs-linux:xfs-kern:169276a

fs/xfs/linux/xfs_buf.c

@@ -165,8 +165,6 @@ _bhash(
  * Mapping of multi-page buffers into contiguous virtual space
  */
 
-STATIC void *pagebuf_mapout_locked(xfs_buf_t *);
-
 typedef struct a_list {
 	void		*vm_addr;
 	struct a_list	*next;
@@ -288,67 +286,53 @@ _pagebuf_get_pages(
 }
 
 /*
- * Walk a pagebuf releasing all the pages contained within it.
+ *	Frees pb_pages if it was malloced.
  */
-STATIC inline void
-_pagebuf_freepages(
-	xfs_buf_t		*pb)
+STATIC void
+_pagebuf_free_pages(
+	xfs_buf_t	*bp)
 {
-	int			buf_index;
-
-	for (buf_index = 0; buf_index < pb->pb_page_count; buf_index++) {
-		struct page	*page = pb->pb_pages[buf_index];
-
-		if (page) {
-			pb->pb_pages[buf_index] = NULL;
-			page_cache_release(page);
-		}
+	if (bp->pb_pages != bp->pb_page_array) {
+		kmem_free(bp->pb_pages,
+			  bp->pb_page_count * sizeof(struct page *));
 	}
 }
 
 /*
- *	pagebuf_free
+ *	Releases the specified buffer.
  *
- *	pagebuf_free releases the specified buffer.  The modification
- *	state of any associated pages is left unchanged.
+ * 	The modification state of any associated pages is left unchanged.
+ * 	The buffer most not be on any hash - use pagebuf_rele instead for
+ * 	hashed and refcounted buffers
  */
 void
 pagebuf_free(
-	xfs_buf_t		*pb)
+	xfs_buf_t		*bp)
 {
-	PB_TRACE(pb, "free", 0);
+	PB_TRACE(bp, "free", 0);
 
-	ASSERT(list_empty(&pb->pb_hash_list));
+	ASSERT(list_empty(&bp->pb_hash_list));
 
-	/* release any virtual mapping */ ;
-	if (pb->pb_flags & _PBF_ADDR_ALLOCATED) {
-		void *vaddr = pagebuf_mapout_locked(pb);
-		if (vaddr) {
-			free_address(vaddr);
-		}
-	}
+	if (bp->pb_flags & _PBF_PAGE_CACHE) {
+		uint		i;
+
+		if ((bp->pb_flags & PBF_MAPPED) && (bp->pb_page_count > 1))
+			free_address(bp->pb_addr - bp->pb_offset);
 
-	if (pb->pb_flags & _PBF_MEM_ALLOCATED) {
-		if (pb->pb_pages) {
-			if (pb->pb_flags & _PBF_MEM_SLAB) {
+		for (i = 0; i < bp->pb_page_count; i++)
+			page_cache_release(bp->pb_pages[i]);
+		_pagebuf_free_pages(bp);
+	} else if (bp->pb_flags & _PBF_KMEM_ALLOC) {
 		 /*
-				  * XXX: bp->pb_count_desired might be incorrect
-				  * (see pagebuf_associate_memory for details),
-				  * but fortunately the Linux version of
-				  * kmem_free ignores the len argument..
+		  * XXX(hch): bp->pb_count_desired might be incorrect (see
+		  * pagebuf_associate_memory for details), but fortunately
+		  * the Linux version of kmem_free ignores the len argument..
 		  */
-				kmem_free(pb->pb_addr, pb->pb_count_desired);
-			} else {
-				_pagebuf_freepages(pb);
-			}
-			if (pb->pb_pages != pb->pb_page_array)
-				kfree(pb->pb_pages);
-			pb->pb_pages = NULL;
-		}
-		pb->pb_flags &= ~(_PBF_MEM_ALLOCATED|_PBF_MEM_SLAB);
+		kmem_free(bp->pb_addr, bp->pb_count_desired);
+		_pagebuf_free_pages(bp);
 	}
 
-	pagebuf_deallocate(pb);
+	pagebuf_deallocate(bp);
 }
 
 /*
@@ -443,7 +427,7 @@ _pagebuf_lookup_pages(
 			unlock_page(bp->pb_pages[i]);
 	}
 
-	bp->pb_flags |= (_PBF_PAGECACHE|_PBF_MEM_ALLOCATED);
+	bp->pb_flags |= _PBF_PAGE_CACHE;
 
 	if (page_count) {
 		/* if we have any uptodate pages, mark that in the buffer */
@@ -478,7 +462,7 @@ _pagebuf_map_pages(
 		if (unlikely(bp->pb_addr == NULL))
 			return -ENOMEM;
 		bp->pb_addr += bp->pb_offset;
-		bp->pb_flags |= PBF_MAPPED | _PBF_ADDR_ALLOCATED;
+		bp->pb_flags |= PBF_MAPPED;
 	}
 
 	return 0;
@@ -584,10 +568,7 @@ _pagebuf_find(				/* find buffer for block	*/
 	}
 
 	if (pb->pb_flags & PBF_STALE)
-		pb->pb_flags &= PBF_MAPPED | \
-				_PBF_ADDR_ALLOCATED | \
-				_PBF_MEM_ALLOCATED | \
-				_PBF_MEM_SLAB;
+		pb->pb_flags &= PBF_MAPPED;
 	PB_TRACE(pb, "got_lock", 0);
 	XFS_STATS_INC(pb_get_locked);
 	return (pb);
@@ -789,9 +770,9 @@ pagebuf_associate_memory(
 		page_count++;
 
 	/* Free any previous set of page pointers */
-	if (pb->pb_pages && (pb->pb_pages != pb->pb_page_array)) {
-		kfree(pb->pb_pages);
-	}
+	if (pb->pb_pages)
+		_pagebuf_free_pages(pb);
+
 	pb->pb_pages = NULL;
 	pb->pb_addr = mem;
 
@@ -856,7 +837,7 @@ pagebuf_get_no_daddr(
 	error = pagebuf_associate_memory(bp, data, len);
 	if (error)
 		goto fail_free_mem;
-	bp->pb_flags |= (_PBF_MEM_ALLOCATED | _PBF_MEM_SLAB);
+	bp->pb_flags |= _PBF_KMEM_ALLOC;
 
 	pagebuf_unlock(bp);
 
@@ -1189,9 +1170,9 @@ pagebuf_iostart(			/* start I/O on a buffer	  */
 	}
 
 	pb->pb_flags &= ~(PBF_READ | PBF_WRITE | PBF_ASYNC | PBF_DELWRI | \
-			PBF_READ_AHEAD | PBF_RUN_QUEUES);
+			PBF_READ_AHEAD | _PBF_RUN_QUEUES);
 	pb->pb_flags |= flags & (PBF_READ | PBF_WRITE | PBF_ASYNC | \
-			PBF_READ_AHEAD | PBF_RUN_QUEUES);
+			PBF_READ_AHEAD | _PBF_RUN_QUEUES);
 
 	BUG_ON(pb->pb_bn == XFS_BUF_DADDR_NULL);
 
@@ -1378,8 +1359,8 @@ _pagebuf_ioapply(
 		pagebuf_ioerror(pb, EIO);
 	}
 
-	if (pb->pb_flags & PBF_RUN_QUEUES) {
-		pb->pb_flags &= ~PBF_RUN_QUEUES;
+	if (pb->pb_flags & _PBF_RUN_QUEUES) {
+		pb->pb_flags &= ~_PBF_RUN_QUEUES;
 		if (atomic_read(&pb->pb_io_remaining) > 1)
 			blk_run_address_space(pb->pb_target->pbr_mapping);
 	}
@@ -1436,25 +1417,6 @@ pagebuf_iowait(
 	return pb->pb_error;
 }
 
-STATIC void *
-pagebuf_mapout_locked(
-	xfs_buf_t		*pb)
-{
-	void			*old_addr = NULL;
-
-	if (pb->pb_flags & PBF_MAPPED) {
-		if (pb->pb_flags & _PBF_ADDR_ALLOCATED)
-			old_addr = pb->pb_addr - pb->pb_offset;
-		pb->pb_addr = NULL;
-		pb->pb_flags &= ~(PBF_MAPPED | _PBF_ADDR_ALLOCATED);
-	}
-
-	return old_addr;	/* Caller must free the address space,
-				 * we are under a spin lock, probably
-				 * not safe to do vfree here
-				 */
-}
-
 caddr_t
 pagebuf_offset(
 	xfs_buf_t		*pb,

fs/xfs/linux/xfs_buf.h

@@ -73,26 +73,22 @@ typedef enum page_buf_flags_e {		/* pb_flags values */
 	PBF_ASYNC = (1 << 4),   /* initiator will not wait for completion  */
 	PBF_NONE = (1 << 5),    /* buffer not read at all                  */
 	PBF_DELWRI = (1 << 6),  /* buffer has dirty pages                  */
-	PBF_STALE = (1 << 10),	/* buffer has been staled, do not find it  */
-	PBF_FS_MANAGED = (1 << 11), /* filesystem controls freeing memory  */
-	PBF_FS_DATAIOD = (1 << 12), /* schedule IO completion on fs datad  */
+	PBF_STALE = (1 << 7),	/* buffer has been staled, do not find it  */
+	PBF_FS_MANAGED = (1 << 8),  /* filesystem controls freeing memory  */
+	PBF_FS_DATAIOD = (1 << 9),  /* schedule IO completion on fs datad  */
+	PBF_FORCEIO = (1 << 10),    /* ignore any cache state		   */
+	PBF_FLUSH = (1 << 11),	    /* flush disk write cache		   */
+	PBF_READ_AHEAD = (1 << 12), /* asynchronous read-ahead		   */
 
 	/* flags used only as arguments to access routines */
-	PBF_LOCK = (1 << 13),	/* lock requested			   */
-	PBF_TRYLOCK = (1 << 14), /* lock requested, but do not wait	   */
-	PBF_DONT_BLOCK = (1 << 15), /* do not block in current thread	   */
+	PBF_LOCK = (1 << 14),       /* lock requested			   */
+	PBF_TRYLOCK = (1 << 15),    /* lock requested, but do not wait	   */
+	PBF_DONT_BLOCK = (1 << 16), /* do not block in current thread	   */
 
 	/* flags used only internally */
-	_PBF_PAGECACHE = (1 << 16),	/* backed by pagecache		   */
-	_PBF_ADDR_ALLOCATED = (1 << 19), /* pb_addr space was allocated	   */
-	_PBF_MEM_ALLOCATED = (1 << 20), /* underlying pages are allocated  */
-	_PBF_MEM_SLAB = (1 << 21), /* underlying pages are slab allocated  */
-
-	PBF_FORCEIO = (1 << 22), /* ignore any cache state		   */
-	PBF_FLUSH = (1 << 23),	/* flush disk write cache		   */
-	PBF_READ_AHEAD = (1 << 24), /* asynchronous read-ahead		   */
-	PBF_RUN_QUEUES = (1 << 25), /* run block device task queue	   */
-
+	_PBF_PAGE_CACHE = (1 << 17),/* backed by pagecache		   */
+	_PBF_KMEM_ALLOC = (1 << 18),/* backed by kmem_alloc()		   */
+	_PBF_RUN_QUEUES = (1 << 19),/* run block device task queue	   */
 } page_buf_flags_t;
 
 #define PBF_UPDATE (PBF_READ | PBF_WRITE)
@@ -508,7 +504,7 @@ static inline int	xfs_bawrite(void *mp, xfs_buf_t *bp)
 	bp->pb_fspriv3 = mp;
 	bp->pb_strat = xfs_bdstrat_cb;
 	xfs_buf_undelay(bp);
-	return pagebuf_iostart(bp, PBF_WRITE | PBF_ASYNC | PBF_RUN_QUEUES);
+	return pagebuf_iostart(bp, PBF_WRITE | PBF_ASYNC | _PBF_RUN_QUEUES);
 }
 
 static inline void	xfs_buf_relse(xfs_buf_t *bp)
@@ -545,7 +541,7 @@ static inline int	XFS_bwrite(xfs_buf_t *pb)
 	int	error = 0;
 
 	if (!iowait)
-		pb->pb_flags |= PBF_RUN_QUEUES;
+		pb->pb_flags |= _PBF_RUN_QUEUES;
 
 	xfs_buf_undelay(pb);
 	pagebuf_iostrategy(pb);