patch-2.1.58 linux/fs/smbfs/cache.c

• Lines: 315
• Date: Sun Oct 12 10:17:05 1997
• Orig file: v2.1.57/linux/fs/smbfs/cache.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.57/linux/fs/smbfs/cache.c linux/fs/smbfs/cache.c
@@ -0,0 +1,314 @@
+/*
+ *  cache.c
+ *
+ * Copyright (C) 1997 by Bill Hawes
+ *
+ * Routines to support directory cacheing using the page cache.
+ * Right now this only works for smbfs, but will be generalized
+ * for use with other filesystems.
+ */
+
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/dirent.h>
+#include <linux/smb_fs.h>
+
+#include <asm/page.h>
+
+#define SMBFS_PARANOIA 1
+/* #define SMBFS_DEBUG_VERBOSE 1 */
+
+static inline struct inode * 
+get_cache_inode(struct cache_head *cachep)
+{
+	return (mem_map + MAP_NR((unsigned long) cachep))->inode;
+}
+
+/*
+ * Get a pointer to the cache_head structure,
+ * mapped as the page at offset 0. The page is
+ * kept locked while we're using the cache.
+ */
+struct cache_head *
+smb_get_dircache(struct dentry * dentry)
+{
+	struct inode * inode = dentry->d_inode;
+	struct cache_head * cachep;
+
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_get_dircache: finding cache for %s/%s\n",
+dentry->d_parent->d_name.name, dentry->d_name.name);
+#endif
+	cachep = (struct cache_head *) get_cached_page(inode, 0, 1);
+	if (!cachep)
+		goto out;
+	if (cachep->valid)
+	{
+		struct cache_index * index = cachep->index;
+		struct cache_block * block;
+		unsigned long offset;
+		int i;
+
+		cachep->valid = 0;
+		/*
+		 * Here we only want to find existing cache blocks,
+		 * not add new ones.
+		 */
+		for (i = 0; i < cachep->pages; i++, index++) {
+#ifdef SMBFS_PARANOIA
+if (index->block)
+printk("smb_get_dircache: cache %s/%s has existing block!\n",
+dentry->d_parent->d_name.name, dentry->d_name.name);
+#endif
+			offset = PAGE_SIZE + (i << PAGE_SHIFT);
+			block = (struct cache_block *) get_cached_page(inode,
+								offset, 0);
+			if (!block)
+				goto out;
+			index->block = block;
+		}
+		cachep->valid = 1;
+	}
+out:
+	return cachep;
+}
+
+/*
+ * Unlock and release the data blocks.
+ */
+static void
+smb_free_cache_blocks(struct cache_head * cachep)
+{
+	struct cache_index * index = cachep->index;
+	int i;
+
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_free_cache_blocks: freeing %d blocks\n", cachep->pages);
+#endif
+	for (i = 0; i < cachep->pages; i++, index++)
+	{
+		if (index->block)
+		{
+			put_cached_page((unsigned long) index->block);
+			index->block = NULL;
+		}
+	}
+}
+
+/*
+ * Unlocks and releases the dircache.
+ */
+void
+smb_free_dircache(struct cache_head * cachep)
+{
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_free_dircache: freeing cache\n");
+#endif
+	smb_free_cache_blocks(cachep);
+	put_cached_page((unsigned long) cachep);
+}
+
+/*
+ * Initializes the dircache. We release any existing data blocks,
+ * and then clear the cache_head structure.
+ */
+void
+smb_init_dircache(struct cache_head * cachep)
+{
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_init_dircache: initializing cache, %d blocks\n", cachep->pages);
+#endif
+	smb_free_cache_blocks(cachep);
+	memset(cachep, 0, sizeof(struct cache_head));
+}
+
+/*
+ * Add a new entry to the cache.  This assumes that the
+ * entries are coming in order and are added to the end.
+ */
+void
+smb_add_to_cache(struct cache_head * cachep, struct dirent *entry, off_t fpos)
+{
+	struct inode * inode = get_cache_inode(cachep);
+	struct cache_index * index;
+	struct cache_block * block;
+	unsigned long page_off;
+	unsigned int nent, offset, len = entry->d_reclen;
+	unsigned int needed = len + sizeof(struct cache_entry);
+
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_add_to_cache: cache inode %p, status %d, adding %s at %ld\n",
+inode, cachep->status, entry->d_name, fpos);
+#endif
+	/*
+	 * Don't do anything if we've had an error ...
+	 */
+	if (cachep->status)
+		goto out;
+
+	index = &cachep->index[cachep->idx];
+	if (!index->block)
+		goto get_block;
+
+	/* space available? */
+	if (needed < index->space)
+	{
+	add_entry:
+		nent = index->num_entries;
+		index->num_entries++;
+		index->space -= needed;
+		offset = index->space + 
+			 index->num_entries * sizeof(struct cache_entry);
+		block = index->block;
+		memcpy(&block->cb_data.names[offset], entry->d_name, len);
+		block->cb_data.table[nent].namelen = len;
+		block->cb_data.table[nent].offset = offset;
+		block->cb_data.table[nent].ino = entry->d_ino;
+		cachep->entries++;
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_add_to_cache: added entry %s, len=%d, pos=%ld, entries=%d\n",
+entry->d_name, len, fpos, cachep->entries);
+#endif
+		return;
+	}
+	/*
+	 * This block is full ... advance the index.
+	 */
+	cachep->idx++;
+	if (cachep->idx > NINDEX) /* not likely */
+		goto out_full;
+	index++;
+#ifdef SMBFS_PARANOIA
+if (index->block)
+printk("smb_add_to_cache: new index already has block!\n");
+#endif
+
+	/*
+	 * Get the next cache block
+	 */
+get_block:
+	cachep->pages++;
+	page_off = PAGE_SIZE + (cachep->idx << PAGE_SHIFT);
+	block = (struct cache_block *) get_cached_page(inode, page_off, 1);
+	if (block)
+	{
+		index->block = block;
+		index->space = PAGE_SIZE;
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_add_to_cache: inode=%p, pages=%d, block at %ld\n",
+inode, cachep->pages, page_off);
+#endif
+		goto add_entry;
+	}
+	/*
+	 * On failure, just set the return status ...
+	 */
+out_full:
+	cachep->status = -ENOMEM;
+out:
+	return;
+}
+
+int
+smb_find_in_cache(struct cache_head * cachep, off_t pos, 
+		struct cache_dirent *entry)
+{
+	struct cache_index * index = cachep->index;
+	struct cache_block * block;
+	unsigned int i, nent, offset = 0;
+	off_t next_pos = 2;
+
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_find_in_cache: cache %p, looking for pos=%ld\n", cachep, pos);
+#endif
+	for (i = 0; i < cachep->pages; i++, index++)
+	{
+		if (pos < next_pos)
+			break;
+		nent = pos - next_pos;
+		next_pos += index->num_entries;
+		if (pos >= next_pos)
+			continue; 
+		/*
+		 * The entry is in this block. Note: we return
+		 * then name as a reference with _no_ null byte.
+		 */
+		block = index->block;
+		entry->ino = block->cb_data.table[nent].ino;
+		entry->len = block->cb_data.table[nent].namelen;
+		offset = block->cb_data.table[nent].offset;
+		entry->name = &block->cb_data.names[offset];
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_find_in_cache: found %s, len=%d, pos=%ld\n",
+entry->name, entry->len, pos);
+#endif
+		break;
+	}
+	return offset;
+}
+
+int
+smb_refill_dircache(struct cache_head * cachep, struct dentry *dentry)
+{
+	struct inode * inode = dentry->d_inode;
+	int result;
+
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_refill_dircache: cache %s/%s, blocks=%d\n",
+dentry->d_parent->d_name.name, dentry->d_name.name, cachep->pages);
+#endif
+	/*
+	 * Fill the cache, starting at position 2.
+	 */
+retry:
+	inode->u.smbfs_i.cache_valid = 1;
+	result = smb_proc_readdir(dentry, 2, cachep);
+	if (result < 0)
+	{
+#ifdef SMBFS_PARANOIA
+printk("smb_refill_dircache: readdir failed, result=%d\n", result);
+#endif
+		goto out;
+	}
+
+	/*
+	 * Check whether the cache was invalidated while
+	 * we were doing the scan ...
+	 */
+	if (!inode->u.smbfs_i.cache_valid)
+	{
+#ifdef SMBFS_PARANOIA
+printk("smb_refill_dircache: cache invalidated, retrying\n");
+#endif
+		goto retry;
+	}
+
+	result = cachep->status;
+	if (!result)
+	{
+		cachep->valid = 1;
+	}
+#ifdef SMBFS_DEBUG_VERBOSE
+printk("smb_refill_cache: cache %s/%s status=%d, entries=%d\n",
+dentry->d_parent->d_name.name, dentry->d_name.name,
+cachep->status, cachep->entries);
+#endif
+
+out:
+	return result;
+}
+
+void
+smb_invalid_dir_cache(struct inode * dir)
+{
+	/*
+	 * Get rid of any unlocked pages, and clear the
+	 * 'valid' flag in case a scan is in progress.
+	 */
+	invalidate_inode_pages(dir);
+	dir->u.smbfs_i.cache_valid = 0;
+}
+