Commit d364fb18 authored by Joakim Tjernlund's avatar Joakim Tjernlund Committed by David Woodhouse
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[JFFS2] Reduce time for which erase_free_sem is held during erase. 



With current desing erase_free_sem is locked every time the flash
block is being erased. For NOR flashes - ~1 second is needed to erase
single flash block. In the worst case scenario erase_free_sem may be
locked for a couple of seconds when the number of blocks is being
erased (e.g. after large file was removed). When erase_free_sem is
locked all read/write operations for given JFFS2 partition are locked
too - in effect from time to time access to the JFFS2 partition is
locked for a number of seconds. This fix makes critical section in
flash erasing procedure shorter - now erase_free_sem is locked around
erase_completion_lock spinlock only.

Originally from Radoslaw Bisewski
Signed-off-by: default avatarJoakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
parent f79c4498

fs/jffs2/erase.c

+20 −2
Original line number Diff line number Diff line
@@ -50,12 +50,14 @@ static void jffs2_erase_block(struct jffs2_sb_info *c, 
	instr = kmalloc(sizeof(struct erase_info) + sizeof(struct erase_priv_struct), GFP_KERNEL);

	if (!instr) {

		printk(KERN_WARNING "kmalloc for struct erase_info in jffs2_erase_block failed. Refiling block for later\n");

		down(&c->erase_free_sem);

		spin_lock(&c->erase_completion_lock);

		list_move(&jeb->list, &c->erase_pending_list);

		c->erasing_size -= c->sector_size;

		c->dirty_size += c->sector_size;

		jeb->dirty_size = c->sector_size;

		spin_unlock(&c->erase_completion_lock);

		up(&c->erase_free_sem);

		return;

	}
@@ -82,12 +84,14 @@ static void jffs2_erase_block(struct jffs2_sb_info *c, 
	if (ret == -ENOMEM || ret == -EAGAIN) {

		/* Erase failed immediately. Refile it on the list */

		D1(printk(KERN_DEBUG "Erase at 0x%08x failed: %d. Refiling on erase_pending_list\n", jeb->offset, ret));

		down(&c->erase_free_sem);

		spin_lock(&c->erase_completion_lock);

		list_move(&jeb->list, &c->erase_pending_list);

		c->erasing_size -= c->sector_size;

		c->dirty_size += c->sector_size;

		jeb->dirty_size = c->sector_size;

		spin_unlock(&c->erase_completion_lock);

		up(&c->erase_free_sem);

		return;

	}
@@ -114,6 +118,7 @@ void jffs2_erase_pending_blocks(struct jffs2_sb_info *c, int count) 
			jeb = list_entry(c->erase_complete_list.next, struct jffs2_eraseblock, list);

			list_del(&jeb->list);

			spin_unlock(&c->erase_completion_lock);

			up(&c->erase_free_sem);

			jffs2_mark_erased_block(c, jeb);



			if (!--count) {
@@ -134,6 +139,7 @@ void jffs2_erase_pending_blocks(struct jffs2_sb_info *c, int count) 
			jffs2_free_jeb_node_refs(c, jeb);

			list_add(&jeb->list, &c->erasing_list);

			spin_unlock(&c->erase_completion_lock);

			up(&c->erase_free_sem);



			jffs2_erase_block(c, jeb);
@@ -143,22 +149,24 @@ void jffs2_erase_pending_blocks(struct jffs2_sb_info *c, int count) 


		/* Be nice */

		yield();

		down(&c->erase_free_sem);

		spin_lock(&c->erase_completion_lock);

	}



	spin_unlock(&c->erase_completion_lock);

	up(&c->erase_free_sem);

 done:

	D1(printk(KERN_DEBUG "jffs2_erase_pending_blocks completed\n"));



	up(&c->erase_free_sem);

}



static void jffs2_erase_succeeded(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)

{

	D1(printk(KERN_DEBUG "Erase completed successfully at 0x%08x\n", jeb->offset));

	down(&c->erase_free_sem);

	spin_lock(&c->erase_completion_lock);

	list_move_tail(&jeb->list, &c->erase_complete_list);

	spin_unlock(&c->erase_completion_lock);

	up(&c->erase_free_sem);

	/* Ensure that kupdated calls us again to mark them clean */

	jffs2_erase_pending_trigger(c);

}
@@ -172,22 +180,26 @@ static void jffs2_erase_failed(struct jffs2_sb_info *c, struct jffs2_eraseblock 
		   failed too many times. */

		if (!jffs2_write_nand_badblock(c, jeb, bad_offset)) {

			/* We'd like to give this block another try. */

			down(&c->erase_free_sem);

			spin_lock(&c->erase_completion_lock);

			list_move(&jeb->list, &c->erase_pending_list);

			c->erasing_size -= c->sector_size;

			c->dirty_size += c->sector_size;

			jeb->dirty_size = c->sector_size;

			spin_unlock(&c->erase_completion_lock);

			up(&c->erase_free_sem);

			return;

		}

	}



	down(&c->erase_free_sem);

	spin_lock(&c->erase_completion_lock);

	c->erasing_size -= c->sector_size;

	c->bad_size += c->sector_size;

	list_move(&jeb->list, &c->bad_list);

	c->nr_erasing_blocks--;

	spin_unlock(&c->erase_completion_lock);

	up(&c->erase_free_sem);

	wake_up(&c->erase_wait);

}
@@ -444,6 +456,7 @@ static void jffs2_mark_erased_block(struct jffs2_sb_info *c, struct jffs2_eraseb 
		jffs2_link_node_ref(c, jeb, jeb->offset | REF_NORMAL, c->cleanmarker_size, NULL);

	}



	down(&c->erase_free_sem);

	spin_lock(&c->erase_completion_lock);

	c->erasing_size -= c->sector_size;

	c->free_size += jeb->free_size;
@@ -456,23 +469,28 @@ static void jffs2_mark_erased_block(struct jffs2_sb_info *c, struct jffs2_eraseb 
	c->nr_erasing_blocks--;

	c->nr_free_blocks++;

	spin_unlock(&c->erase_completion_lock);

	up(&c->erase_free_sem);

	wake_up(&c->erase_wait);

	return;



filebad:

	down(&c->erase_free_sem);

	spin_lock(&c->erase_completion_lock);

	/* Stick it on a list (any list) so erase_failed can take it

	   right off again.  Silly, but shouldn't happen often. */

	list_add(&jeb->list, &c->erasing_list);

	spin_unlock(&c->erase_completion_lock);

	up(&c->erase_free_sem);

	jffs2_erase_failed(c, jeb, bad_offset);

	return;



refile:

	/* Stick it back on the list from whence it came and come back later */

	jffs2_erase_pending_trigger(c);

	down(&c->erase_free_sem);

	spin_lock(&c->erase_completion_lock);

	list_add(&jeb->list, &c->erase_complete_list);

	spin_unlock(&c->erase_completion_lock);

	up(&c->erase_free_sem);

	return;

}

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