Messages in this thread Patch in this message | | | Date | Sun, 18 Apr 2004 00:06:47 +0200 | From | Christoph Hellwig <> | Subject | [PATCH 3/3] lockfs - dm bits |
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This patch makes the device mapper use the new freeze_bdev/thaw_bdev interface. Extracted from Chris Mason's patch.
--- 1.42/drivers/md/dm.c Mon Apr 12 19:55:18 2004 +++ edited/drivers/md/dm.c Sat Apr 17 19:38:36 2004 @@ -12,6 +12,7 @@ #include <linux/moduleparam.h> #include <linux/blkpg.h> #include <linux/bio.h> +#include <linux/buffer_head.h> #include <linux/mempool.h> #include <linux/slab.h> @@ -46,6 +47,7 @@ */ #define DMF_BLOCK_IO 0 #define DMF_SUSPENDED 1 +#define DMF_FS_LOCKED 2 struct mapped_device { struct rw_semaphore lock; @@ -80,6 +82,11 @@ */ uint32_t event_nr; wait_queue_head_t eventq; + + /* + * freeze/thaw support require holding onto a super block + */ + struct super_block *frozen_sb; }; #define MIN_IOS 256 @@ -882,6 +889,52 @@ } /* + * Functions to lock and unlock any filesystem running on the + * device. + */ +static int __lock_fs(struct mapped_device *md) +{ + struct block_device *bdev; + + if (test_and_set_bit(DMF_FS_LOCKED, &md->flags)) + return 0; + + bdev = bdget_disk(md->disk, 0); + if (!bdev) { + DMWARN("bdget failed in __lock_fs"); + return -ENOMEM; + } + + WARN_ON(md->frozen_sb); + md->frozen_sb = freeze_bdev(bdev); + /* don't bdput right now, we don't want the bdev + * to go away while it is locked. We'll bdput + * in __unlock_fs + */ + return 0; +} + +static int __unlock_fs(struct mapped_device *md) +{ + struct block_device *bdev; + + if (!test_and_clear_bit(DMF_FS_LOCKED, &md->flags)) + return 0; + + bdev = bdget_disk(md->disk, 0); + if (!bdev) { + DMWARN("bdget failed in __unlock_fs"); + return -ENOMEM; + } + + thaw_bdev(bdev, md->frozen_sb); + md->frozen_sb = NULL; + bdput(bdev); + bdput(bdev); + return 0; +} + +/* * We need to be able to change a mapping table under a mounted * filesystem. For example we might want to move some data in * the background. Before the table can be swapped with @@ -893,13 +946,27 @@ struct dm_table *map; DECLARE_WAITQUEUE(wait, current); - down_write(&md->lock); + /* Flush I/O to the device. */ + down_read(&md->lock); + if (test_bit(DMF_BLOCK_IO, &md->flags)) { + up_read(&md->lock); + return -EINVAL; + } + + __lock_fs(md); + up_read(&md->lock); /* * First we set the BLOCK_IO flag so no more ios will be * mapped. */ + down_write(&md->lock); if (test_bit(DMF_BLOCK_IO, &md->flags)) { + /* + * If we get here we know another thread is + * trying to suspend as well, so we leave the fs + * locked for this thread. + */ up_write(&md->lock); return -EINVAL; } @@ -963,6 +1030,7 @@ def = bio_list_get(&md->deferred); __flush_deferred_io(md, def); up_write(&md->lock); + __unlock_fs(md); dm_table_unplug_all(map); dm_table_put(map); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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