From 061ea8581b2e0ade913c8f5cd845e801976a577b Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Mon, 29 Apr 2024 13:08:12 +0100 Subject: [PATCH] btrfs: preallocate inodes xarray entry to avoid transaction abort When creating a new inode, at btrfs_create_new_inode(), one of the very last steps is to add the inode to the root's inodes xarray. This often requires allocating memory which may fail (even though xarrays have a dedicated kmem_cache which make it less likely to fail), and at that point we are forced to abort the current transaction (as some, but not all, of the inode metadata was added to its subvolume btree). To avoid a transaction abort, preallocate memory for the xarray early at btrfs_create_new_inode(), so that if we fail we don't need to abort the transaction and the insertion into the xarray is guaranteed to succeed. Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index aad4c9daff82..0e667fecfcb2 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5493,7 +5493,7 @@ out: return err; } -static int btrfs_add_inode_to_root(struct btrfs_inode *inode) +static int btrfs_add_inode_to_root(struct btrfs_inode *inode, bool prealloc) { struct btrfs_root *root = inode->root; struct btrfs_inode *existing; @@ -5503,9 +5503,11 @@ static int btrfs_add_inode_to_root(struct btrfs_inode *inode) if (inode_unhashed(&inode->vfs_inode)) return 0; - ret = xa_reserve(&root->inodes, ino, GFP_NOFS); - if (ret) - return ret; + if (prealloc) { + ret = xa_reserve(&root->inodes, ino, GFP_NOFS); + if (ret) + return ret; + } spin_lock(&root->inode_lock); existing = xa_store(&root->inodes, ino, inode, GFP_ATOMIC); @@ -5606,7 +5608,7 @@ struct inode *btrfs_iget_path(struct super_block *s, u64 ino, ret = btrfs_read_locked_inode(inode, path); if (!ret) { - ret = btrfs_add_inode_to_root(BTRFS_I(inode)); + ret = btrfs_add_inode_to_root(BTRFS_I(inode), true); if (ret) { iget_failed(inode); inode = ERR_PTR(ret); @@ -6237,6 +6239,7 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans, struct btrfs_item_batch batch; unsigned long ptr; int ret; + bool xa_reserved = false; path = btrfs_alloc_path(); if (!path) @@ -6251,6 +6254,11 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans, goto out; inode->i_ino = objectid; + ret = xa_reserve(&root->inodes, objectid, GFP_NOFS); + if (ret) + goto out; + xa_reserved = true; + if (args->orphan) { /* * O_TMPFILE, set link count to 0, so that after this point, we @@ -6424,8 +6432,9 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans, } } - ret = btrfs_add_inode_to_root(BTRFS_I(inode)); - if (ret) { + ret = btrfs_add_inode_to_root(BTRFS_I(inode), false); + if (WARN_ON(ret)) { + /* Shouldn't happen, we used xa_reserve() before. */ btrfs_abort_transaction(trans, ret); goto discard; } @@ -6456,6 +6465,9 @@ discard: ihold(inode); discard_new_inode(inode); out: + if (xa_reserved) + xa_release(&root->inodes, objectid); + btrfs_free_path(path); return ret; } -- 2.49.0