[JFFS2] Fix jffs2_reserve_space() when all blocks are pending erasure.

When _all_ the blocks were on the erase_pending_list, we could't find a
block to GC from but there was no _actually_ free space, and
jffs2_reserve_space() would get a little unhappy.

Handle this case by returning -EAGAIN from jffs2_garbage_collect_pass().
There are two callers of that function -- jffs2_flush_wbuf_gc(), which
will interpret it as an error and flush the writebuffer by other means,
and jffs2_reserve_space(), which we modify to respond to -EAGAIN with an
immediate call to jffs2_erase_pending_blocks() and another run round the
loop.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

2 files changed, 11 insertions, 2 deletions

diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
index 26c7992c45ca..bad005664e30 100644
--- a/fs/jffs2/gc.c
+++ b/fs/jffs2/gc.c
@@ -221,7 +221,13 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
                 jeb = jffs2_find_gc_block(c);
 
         if (!jeb) {
-                D1 (printk(KERN_NOTICE "jffs2: Couldn't find erase block to garbage collect!\n"));
+                /* Couldn't find a free block. But maybe we can just erase one and make 'progress'? */
+                if (!list_empty(&c->erase_pending_list)) {
+                        spin_unlock(&c->erase_completion_lock);
+                        mutex_unlock(&c->alloc_sem);
+                        return -EAGAIN;
+                }
+                D1(printk(KERN_NOTICE "jffs2: Couldn't find erase block to garbage collect!\n"));
                 spin_unlock(&c->erase_completion_lock);
                 mutex_unlock(&c->alloc_sem);
                 return -EIO;
diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index 747a73f0aa4d..9df8f3ef20df 100644
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -116,7 +116,10 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize,
                         spin_unlock(&c->erase_completion_lock);
 
                         ret = jffs2_garbage_collect_pass(c);
-                        if (ret)
+
+                        if (ret == -EAGAIN)
+                                jffs2_erase_pending_blocks(c, 1);
+                        else if (ret)
                                 return ret;
 
                         cond_resched();