btrfs: Support busy loop of write and delete

Reproduce:
 while true; do
   dd if=/dev/zero of=/mnt/btrfs/file count=[75% fs_size]
   rm /mnt/btrfs/file
 done
 Then we can see above loop failed on NO_SPACE.

It it long-term problem since very beginning, because delayed-iput
after rm are not run.

We already have commit_transaction() in alloc_space code, but it is
not triggered in above case.
This patch trigger commit_transaction() to run delayed-iput and
reflash pinned-space to to make write success.

It is based on previous fix of delayed-iput in commit_transaction(),
need to be applied on top of:
btrfs: Fix NO_SPACE bug caused by delayed-iput

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 46cb1d4149124a138391617a0e7ca28e099c1a88..2713dcbc70f79e892c978e093e30bbf4308306d6 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3858,14 +3858,14 @@ int btrfs_check_data_free_space(struct inode *inode, u64 bytes)
        struct btrfs_fs_info *fs_info = root->fs_info;
        u64 used;
        int ret = 0;
-       int committed = 0;
-       int have_pinned_space = 1;
+       int need_commit = 2;
+       int have_pinned_space;
 
        /* make sure bytes are sectorsize aligned */
        bytes = ALIGN(bytes, root->sectorsize);
 
        if (btrfs_is_free_space_inode(inode)) {
-               committed = 1;
+               need_commit = 0;
                ASSERT(current->journal_info);
        }
 
@@ -3915,8 +3915,10 @@ alloc:
                        if (ret < 0) {
                                if (ret != -ENOSPC)
                                        return ret;
-                               else
+                               else {
+                                       have_pinned_space = 1;
                                        goto commit_trans;
+                               }
                        }
 
                        if (!data_sinfo)
@@ -3930,23 +3932,23 @@ alloc:
                 * allocation, and no removed chunk in current transaction,
                 * don't bother committing the transaction.
                 */
-               if (percpu_counter_compare(&data_sinfo->total_bytes_pinned,
-                                          used + bytes -
-                                          data_sinfo->total_bytes) < 0)
-                       have_pinned_space = 0;
+               have_pinned_space = percpu_counter_compare(
+                       &data_sinfo->total_bytes_pinned,
+                       used + bytes - data_sinfo->total_bytes);
                spin_unlock(&data_sinfo->lock);
 
                /* commit the current transaction and try again */
 commit_trans:
-               if (!committed &&
+               if (need_commit &&
                    !atomic_read(&root->fs_info->open_ioctl_trans)) {
-                       committed = 1;
+                       need_commit--;
 
                        trans = btrfs_join_transaction(root);
                        if (IS_ERR(trans))
                                return PTR_ERR(trans);
-                       if (have_pinned_space ||
-                           trans->transaction->have_free_bgs) {
+                       if (have_pinned_space >= 0 ||
+                           trans->transaction->have_free_bgs ||
+                           need_commit > 0) {
                                ret = btrfs_commit_transaction(trans, root);
                                if (ret)
                                        return ret;