logfs: commit reservations under space pressure

Ensures we only return -ENOSPC when there really is no space.

Signed-off-by: Joern Engel <joern@logfs.org>

diff --git a/fs/logfs/file.c b/fs/logfs/file.c
index 370f367..bf9b1cf 100644 (file)
--- a/fs/logfs/file.c
+++ b/fs/logfs/file.c
@@ -161,7 +161,17 @@ static int logfs_writepage(struct page *page, struct writeback_control *wbc)
 
 static void logfs_invalidatepage(struct page *page, unsigned long offset)
 {
-       move_page_to_btree(page);
+       struct logfs_block *block = logfs_block(page);
+
+       if (block->reserved_bytes) {
+               struct super_block *sb = page->mapping->host->i_sb;
+               struct logfs_super *super = logfs_super(sb);
+
+               super->s_dirty_pages -= block->reserved_bytes;
+               block->ops->free_block(sb, block);
+               BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
+       } else
+               move_page_to_btree(page);
        BUG_ON(PagePrivate(page) || page->private);
 }
 

diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index 32bf556..26a9458 100644 (file)
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -394,6 +394,7 @@ struct logfs_super {
        int      s_lock_count;
        mempool_t *s_block_pool;                /* struct logfs_block pool */
        mempool_t *s_shadow_pool;               /* struct logfs_shadow pool */
+       struct list_head s_writeback_list;      /* writeback pages */
        /*
         * Space accounting:
         * - s_used_bytes specifies space used to store valid data objects.

diff --git a/fs/logfs/readwrite.c b/fs/logfs/readwrite.c
index e37cee3..0718d11 100644 (file)
--- a/fs/logfs/readwrite.c
+++ b/fs/logfs/readwrite.c
@@ -1095,17 +1095,25 @@ static int logfs_reserve_bytes(struct inode *inode, int bytes)
 int get_page_reserve(struct inode *inode, struct page *page)
 {
        struct logfs_super *super = logfs_super(inode->i_sb);
+       struct logfs_block *block = logfs_block(page);
        int ret;
 
-       if (logfs_block(page) && logfs_block(page)->reserved_bytes)
+       if (block && block->reserved_bytes)
                return 0;
 
        logfs_get_wblocks(inode->i_sb, page, WF_LOCK);
-       ret = logfs_reserve_bytes(inode, 6 * LOGFS_MAX_OBJECTSIZE);
+       while ((ret = logfs_reserve_bytes(inode, 6 * LOGFS_MAX_OBJECTSIZE)) &&
+                       !list_empty(&super->s_writeback_list)) {
+               block = list_entry(super->s_writeback_list.next,
+                               struct logfs_block, alias_list);
+               block->ops->write_block(block);
+       }
        if (!ret) {
                alloc_data_block(inode, page);
-               logfs_block(page)->reserved_bytes += 6 * LOGFS_MAX_OBJECTSIZE;
+               block = logfs_block(page);
+               block->reserved_bytes += 6 * LOGFS_MAX_OBJECTSIZE;
                super->s_dirty_pages += 6 * LOGFS_MAX_OBJECTSIZE;
+               list_move_tail(&block->alias_list, &super->s_writeback_list);
        }
        logfs_put_wblocks(inode->i_sb, page, WF_LOCK);
        return ret;
@@ -2251,6 +2259,7 @@ int logfs_init_rw(struct super_block *sb)
        int min_fill = 3 * super->s_no_blocks;
 
        INIT_LIST_HEAD(&super->s_object_alias);
+       INIT_LIST_HEAD(&super->s_writeback_list);
        mutex_init(&super->s_write_mutex);
        super->s_block_pool = mempool_create_kmalloc_pool(min_fill,
                        sizeof(struct logfs_block));