Fix deadlock when snapshotting a snapshot and remove redundant chunk iobuf.

diff --git a/kernel/common/dm-snapshot.c b/kernel/common/dm-snapshot.c
index 81ca4b366ee3c2ad9cc0916860676a698ced0512..452f0b620e8208d41714fa9ecbbbd831ad2d0e82 100644 (file)
--- a/kernel/common/dm-snapshot.c
+++ b/kernel/common/dm-snapshot.c
@@ -71,7 +71,6 @@ struct snapshot_c {
        int    current_metadata_number;/* Index into mythical extent array */
        int    highest_metadata_entry; /* Number of metadata entries in the disk_cow array */
        int    md_entries_per_block;   /* Number of metadata entries per hard disk block */
-       struct kiobuf *iobuf;          /* kiobuf for doing I/O to chunks and cows */
        struct kiobuf *cow_iobuf;      /* kiobuf for doing I/O to header & metadata */
        struct list_head *hash_table;  /* Hash table for looking up COW data */
        struct origin_list *origin;    /* So we can get at the locking rwsem */
@@ -236,14 +235,15 @@ static void copy_callback(copy_cb_reason_t reason, void *context, long arg)
                /* Submit any pending write BHs */
                down_write(&ex->snap->origin->lock);
                bh = ex->bh;
+               ex->bh = NULL;
+               up_write(&ex->snap->origin->lock);
+
                while (bh) {
                        struct buffer_head *nextbh = bh->b_reqnext;
                        bh->b_reqnext = NULL;
                        generic_make_request(WRITE, bh);
                        bh = nextbh;
                }
-               ex->bh = NULL;
-               up_write(&ex->snap->origin->lock);
        }
 
        /* Read/write error - snapshot is unusable */
@@ -850,15 +850,6 @@ static int snapshot_ctr(struct dm_table *t, offset_t b, offset_t l,
        if (alloc_hash_table(lc) == -1)
                goto bad_putdev;
 
-       /* Allocate and set up iobuf */
-       *context = "Unable to allocate iovec";
-       if (alloc_kiovec(1, &lc->iobuf))
-               goto bad_free1;
-
-       *context = "Unable to allocate I/O buffer space";
-       if (alloc_iobuf_pages(lc->iobuf, chunk_size))
-               goto bad_free2;
-
        /* Check the persistent flag - done here because we need the iobuf
           to check the LV header */
        if ((*persistent & 0x5f) == 'P') {
@@ -871,7 +862,7 @@ static int snapshot_ctr(struct dm_table *t, offset_t b, offset_t l,
        /* For a persistent snapshot allocate the COW iobuf and set associated variables */
        if (lc->persistent) {
                if (setup_persistent_snapshot(lc, blocksize, context))
-                       goto bad_free3;
+                       goto bad_free1;
        }
 
        /* Flush IO to the origin device */
@@ -886,20 +877,16 @@ static int snapshot_ctr(struct dm_table *t, offset_t b, offset_t l,
        r = -EINVAL;
        *context = "Cannot register snapshot origin";
        if (!register_snapshot(lc->origin_dev->dev, lc))
-           goto bad_free4;
+           goto bad_free2;
 
        *context = lc;
        return 0;
 
- bad_free4:
+ bad_free2:
        if (lc->persistent) {
                unmap_kiobuf(lc->cow_iobuf);
                free_kiovec(1, &lc->cow_iobuf);
        }
- bad_free3:
-       unmap_kiobuf(lc->iobuf);
- bad_free2:
-       free_kiovec(1, &lc->iobuf);
  bad_free1:
        vfree(lc->hash_table);
  bad_putdev:
@@ -920,8 +907,6 @@ static void snapshot_dtr(struct dm_table *t, void *c)
 
        /* Deallocate memory used */
        free_exception_table(lc);
-       unmap_kiobuf(lc->iobuf);
-       free_kiovec(1, &lc->iobuf);
        if (lc->persistent) {
                unmap_kiobuf(lc->cow_iobuf);
                free_kiovec(1, &lc->cow_iobuf);