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>

1 files changed, 12 insertions, 3 deletions

diff --git a/fs/logfs/readwrite.c b/fs/logfs/readwrite.c
index e37cee3b1007..0718d112a1a5 100644
--- 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));