1 files changed, 84 insertions, 28 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index da828cf5e8f8..d2e732d7af52 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -108,6 +108,13 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
 
 static int btrfs_dirty_inode(struct inode *inode);
 
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+void btrfs_test_inode_set_ops(struct inode *inode)
+{
+        BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
+}
+#endif
+
 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
                                      struct inode *inode,  struct inode *dir,
                                      const struct qstr *qstr)
@@ -1542,30 +1549,17 @@ static void btrfs_split_extent_hook(struct inode *inode,
                 u64 new_size;
 
                 /*
-                 * We need the largest size of the remaining extent to see if we
-                 * need to add a new outstanding extent.  Think of the following
-                 * case
-                 *
-                 * [MEAX_EXTENT_SIZEx2 - 4k][4k]
-                 *
-                 * The new_size would just be 4k and we'd think we had enough
-                 * outstanding extents for this if we only took one side of the
-                 * split, same goes for the other direction.  We need to see if
-                 * the larger size still is the same amount of extents as the
-                 * original size, because if it is we need to add a new
-                 * outstanding extent.  But if we split up and the larger size
-                 * is less than the original then we are good to go since we've
-                 * already accounted for the extra extent in our original
-                 * accounting.
+                 * See the explanation in btrfs_merge_extent_hook, the same
+                 * applies here, just in reverse.
                  */
                 new_size = orig->end - split + 1;
-                if ((split - orig->start) > new_size)
-                        new_size = split - orig->start;
-
-                num_extents = div64_u64(size + BTRFS_MAX_EXTENT_SIZE - 1,
+                num_extents = div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
                                         BTRFS_MAX_EXTENT_SIZE);
-                if (div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
-                              BTRFS_MAX_EXTENT_SIZE) < num_extents)
+                new_size = split - orig->start;
+                num_extents += div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
+                                        BTRFS_MAX_EXTENT_SIZE);
+                if (div64_u64(size + BTRFS_MAX_EXTENT_SIZE - 1,
+                              BTRFS_MAX_EXTENT_SIZE) >= num_extents)
                         return;
         }
 
@@ -1591,8 +1585,10 @@ static void btrfs_merge_extent_hook(struct inode *inode,
         if (!(other->state & EXTENT_DELALLOC))
                 return;
 
-        old_size = other->end - other->start + 1;
-        new_size = old_size + (new->end - new->start + 1);
+        if (new->start > other->start)
+                new_size = new->end - other->start + 1;
+        else
+                new_size = other->end - new->start + 1;
 
         /* we're not bigger than the max, unreserve the space and go */
         if (new_size <= BTRFS_MAX_EXTENT_SIZE) {
@@ -1603,13 +1599,32 @@ static void btrfs_merge_extent_hook(struct inode *inode,
         }
 
         /*
-         * If we grew by another max_extent, just return, we want to keep that
-         * reserved amount.
+         * We have to add up either side to figure out how many extents were
+         * accounted for before we merged into one big extent.  If the number of
+         * extents we accounted for is <= the amount we need for the new range
+         * then we can return, otherwise drop.  Think of it like this
+         *
+         * [ 4k][MAX_SIZE]
+         *
+         * So we've grown the extent by a MAX_SIZE extent, this would mean we
+         * need 2 outstanding extents, on one side we have 1 and the other side
+         * we have 1 so they are == and we can return.  But in this case
+         *
+         * [MAX_SIZE+4k][MAX_SIZE+4k]
+         *
+         * Each range on their own accounts for 2 extents, but merged together
+         * they are only 3 extents worth of accounting, so we need to drop in
+         * this case.
          */
+        old_size = other->end - other->start + 1;
         num_extents = div64_u64(old_size + BTRFS_MAX_EXTENT_SIZE - 1,
                                 BTRFS_MAX_EXTENT_SIZE);
+        old_size = new->end - new->start + 1;
+        num_extents += div64_u64(old_size + BTRFS_MAX_EXTENT_SIZE - 1,
+                                 BTRFS_MAX_EXTENT_SIZE);
+
         if (div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
-                      BTRFS_MAX_EXTENT_SIZE) > num_extents)
+                      BTRFS_MAX_EXTENT_SIZE) >= num_extents)
                 return;
 
         spin_lock(&BTRFS_I(inode)->lock);
@@ -1686,6 +1701,10 @@ static void btrfs_set_bit_hook(struct inode *inode,
                         spin_unlock(&BTRFS_I(inode)->lock);
                 }
 
+                /* For sanity tests */
+                if (btrfs_test_is_dummy_root(root))
+                        return;
+
                 __percpu_counter_add(&root->fs_info->delalloc_bytes, len,
                                      root->fs_info->delalloc_batch);
                 spin_lock(&BTRFS_I(inode)->lock);
@@ -1741,6 +1760,10 @@ static void btrfs_clear_bit_hook(struct inode *inode,
                     root != root->fs_info->tree_root)
                         btrfs_delalloc_release_metadata(inode, len);
 
+                /* For sanity tests. */
+                if (btrfs_test_is_dummy_root(root))
+                        return;
+
                 if (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID
                     && do_list && !(state->state & EXTENT_NORESERVE))
                         btrfs_free_reserved_data_space(inode, len);
@@ -7213,7 +7236,7 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
         u64 start = iblock << inode->i_blkbits;
         u64 lockstart, lockend;
         u64 len = bh_result->b_size;
-        u64 orig_len = len;
+        u64 *outstanding_extents = NULL;
         int unlock_bits = EXTENT_LOCKED;
         int ret = 0;
 
@@ -7225,6 +7248,16 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
         lockstart = start;
         lockend = start + len - 1;
 
+        if (current->journal_info) {
+                /*
+                 * Need to pull our outstanding extents and set journal_info to NULL so
+                 * that anything that needs to check if there's a transction doesn't get
+                 * confused.
+                 */
+                outstanding_extents = current->journal_info;
+                current->journal_info = NULL;
+        }
+
         /*
          * If this errors out it's because we couldn't invalidate pagecache for
          * this range and we need to fallback to buffered.
@@ -7348,11 +7381,20 @@ unlock:
                 if (start + len > i_size_read(inode))
                         i_size_write(inode, start + len);
 
-                if (len < orig_len) {
+                /*
+                 * If we have an outstanding_extents count still set then we're
+                 * within our reservation, otherwise we need to adjust our inode
+                 * counter appropriately.
+                 */
+                if (*outstanding_extents) {
+                        (*outstanding_extents)--;
+                } else {
                         spin_lock(&BTRFS_I(inode)->lock);
                         BTRFS_I(inode)->outstanding_extents++;
                         spin_unlock(&BTRFS_I(inode)->lock);
                 }
+
+                current->journal_info = outstanding_extents;
                 btrfs_free_reserved_data_space(inode, len);
         }
 
@@ -7376,6 +7418,8 @@ unlock:
 unlock_err:
         clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend,
                          unlock_bits, 1, 0, &cached_state, GFP_NOFS);
+        if (outstanding_extents)
+                current->journal_info = outstanding_extents;
         return ret;
 }
 
@@ -8075,6 +8119,7 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
 {
         struct file *file = iocb->ki_filp;
         struct inode *inode = file->f_mapping->host;
+        u64 outstanding_extents = 0;
         size_t count = 0;
         int flags = 0;
         bool wakeup = true;
@@ -8112,6 +8157,16 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
                 ret = btrfs_delalloc_reserve_space(inode, count);
                 if (ret)
                         goto out;
+                outstanding_extents = div64_u64(count +
+                                                BTRFS_MAX_EXTENT_SIZE - 1,
+                                                BTRFS_MAX_EXTENT_SIZE);
+
+                /*
+                 * We need to know how many extents we reserved so that we can
+                 * do the accounting properly if we go over the number we
+                 * originally calculated.  Abuse current->journal_info for this.
+                 */
+                current->journal_info = &outstanding_extents;
         } else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
                                      &BTRFS_I(inode)->runtime_flags)) {
                 inode_dio_done(inode);
@@ -8124,6 +8179,7 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
                         iter, offset, btrfs_get_blocks_direct, NULL,
                         btrfs_submit_direct, flags);
         if (rw & WRITE) {
+                current->journal_info = NULL;
                 if (ret < 0 && ret != -EIOCBQUEUED)
                         btrfs_delalloc_release_space(inode, count);
                 else if (ret >= 0 && (size_t)ret < count)