From fdfa20c1631210d0ca218689204682ea80e170e3 Mon Sep 17 00:00:00 2001 From: Paul Taysom Date: Tue, 4 Jun 2013 14:42:40 -0700 Subject: mmc: reordered shutdown sequence in mmc_bld_remove_req We had a multi-partition SD-Card with two ext2 file systems. The partition table was getting overwritten by a race between the card removal and the unmount of the 2nd ext2 partition. What was observed: 1. Suspend/resume would call to remove the device. The clearing of the device information is done asynchronously. 2. A request is made to unmount the file system (this is called after the removal has started). 3. The remapping table was cleared by the asynchronous part of the device removal. 4. A write request to the super block (block 0 of the partition) was sent down and instead of being remapped to the partition offset, it was remapped to block 0 of the device which is where the partition table is located. 5. Write was queued and written resulting in the overwriting of the partition table with the ext2 super block. 6. The mmc_queue is cleaned up. The mmc card device driver used to access SD cards, was calling del_gendisk before calling mmc_cleanup-queue. The comment in the mmc_blk_remove_req code indicated that it expected del_gendisk to block all further requests from being queued but it doesn't. The mmc driver uses the presences of the mmc_queue to determine if the request should be queued. The fix was to clean up the mmc_queue before the rest of the the delete partition code is called. This prevents the overwriting of the partition table. However, the umount gets an error trying to write the super block. The umount should be issued before the device is removed but that is not always possible. The umount is still needed to cleanup other data structures. Addresses the problem described in http://crbug.com/240815 Signed-off-by: Paul Taysom Signed-off-by: Chris Ball --- drivers/mmc/card/block.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'drivers/mmc') diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index c900d28..59a13fc 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -2185,6 +2185,14 @@ static void mmc_blk_remove_req(struct mmc_blk_data *md) struct mmc_card *card; if (md) { + /* + * Flush remaining requests and free queues. It + * is freeing the queue that stops new requests + * from being accepted. + */ + mmc_cleanup_queue(&md->queue); + if (md->flags & MMC_BLK_PACKED_CMD) + mmc_packed_clean(&md->queue); card = md->queue.card; if (md->disk->flags & GENHD_FL_UP) { device_remove_file(disk_to_dev(md->disk), &md->force_ro); @@ -2193,14 +2201,8 @@ static void mmc_blk_remove_req(struct mmc_blk_data *md) device_remove_file(disk_to_dev(md->disk), &md->power_ro_lock); - /* Stop new requests from getting into the queue */ del_gendisk(md->disk); } - - /* Then flush out any already in there */ - mmc_cleanup_queue(&md->queue); - if (md->flags & MMC_BLK_PACKED_CMD) - mmc_packed_clean(&md->queue); mmc_blk_put(md); } } -- cgit v1.1