From 4227564d44e13748395c3f9afa9c24eb470e6013 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 10 Nov 2015 18:54:00 +0100 Subject: [PATCH] btrfs: allocate root item at snapshot ioctl time The actual snapshot creation is delayed until transaction commit. If we cannot get enough memory for the root item there, we have to fail the whole transaction commit which is bad. So we'll allocate the memory at the ioctl call and pass it along with the pending_snapshot struct. The potential ENOMEM will be returned to the caller of snapshot ioctl. Signed-off-by: David Sterba --- fs/btrfs/ioctl.c | 9 +++++++++ fs/btrfs/transaction.c | 9 +++------ fs/btrfs/transaction.h | 1 + 3 files changed, 13 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index fa25091e10abc..27fc660b0ff33 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -659,6 +659,13 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir, if (!pending_snapshot) return -ENOMEM; + pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item), + GFP_NOFS); + if (!pending_snapshot->root_item) { + ret = -ENOMEM; + goto free_pending; + } + atomic_inc(&root->will_be_snapshoted); smp_mb__after_atomic(); btrfs_wait_for_no_snapshoting_writes(root); @@ -738,6 +745,8 @@ fail: dec_and_free: if (atomic_dec_and_test(&root->will_be_snapshoted)) wake_up_atomic_t(&root->will_be_snapshoted); +free_pending: + kfree(pending_snapshot->root_item); kfree(pending_snapshot); return ret; diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index be8eae80ff657..2074106122d9a 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1325,11 +1325,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, return 0; } - new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS); - if (!new_root_item) { - pending->error = -ENOMEM; - goto root_item_alloc_fail; - } + ASSERT(pending->root_item); + new_root_item = pending->root_item; pending->error = btrfs_find_free_objectid(tree_root, &objectid); if (pending->error) @@ -1562,7 +1559,7 @@ clear_skip_qgroup: btrfs_clear_skip_qgroup(trans); no_free_objectid: kfree(new_root_item); -root_item_alloc_fail: + pending->root_item = NULL; btrfs_free_path(path); return ret; } diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index 64c8221b6165b..b6f9a3c944685 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -137,6 +137,7 @@ struct btrfs_pending_snapshot { struct dentry *dentry; struct inode *dir; struct btrfs_root *root; + struct btrfs_root_item *root_item; struct btrfs_root *snap; struct btrfs_qgroup_inherit *inherit; /* block reservation for the operation */ -- 2.39.5