From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7BB5F4446EF; Wed, 5 Aug 2026 11:54:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785930865; cv=none; b=ebNEn4VT0rDkbdOyzYCEH+K/5NgjtZ7hepAOVVdxk00Tn6ukV33m01NCrQbhdp0AnHPkyHWW6xobphBHvTFRXWNDR7STYQdVicmhJCd4/yQmWWuvhdk73PUyRk5kwSH5inTL7TynLTV9yfzusvVO2kqaUuTu/Bf9biJGp2+e2Wc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785930865; c=relaxed/simple; bh=7+SXTtIRKHTDGlQmrN6xyy3k6eaNtniUyrgH292vTzw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; 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BF18R2zYFQe9K6E5TlFoM5ksYO739yBis7j/A4OjLM2/XCmsjEsl+3uET1RwtRvcQv ENJ04vw/hD3i48LzMED68o6lKd4YddO2HbZWIFm8cCvDflv9KF/e3pacpFS3SQ+6vs PLe94e7P06T/A== Message-ID: <8ebbafc475baff8aedf5e2b2718db867063fab07.camel@kernel.org> Subject: Re: [PATCH v2 2/5] btrfs: split btrfs_insert_delayed_dir_index() into prealloc and commit phases From: Jeff Layton To: Qu Wenruo , Chris Mason , David Sterba Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Date: Wed, 05 Aug 2026 07:54:20 -0400 In-Reply-To: <8b16c994-b322-42c9-b134-47dca5f2682e@suse.com> References: <20260804-btrfs-enomem-v2-0-4d923170e8c1@kernel.org> <20260804-btrfs-enomem-v2-2-4d923170e8c1@kernel.org> <8b16c994-b322-42c9-b134-47dca5f2682e@suse.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-08-05 at 08:44 +0930, 'Qu Wenruo' via Kernel Team wrote: >=20 > =E5=9C=A8 2026/8/5 01:14, Jeff Layton =E5=86=99=E9=81=93: > > Split btrfs_insert_delayed_dir_index() into three functions using a new > > btrfs_dir_index_prealloc struct to bundle the pre-allocated resources: > >=20 > > - btrfs_prealloc_delayed_dir_index(): performs the two GFP_NOFS > > allocations (delayed node + delayed item) that can fail with -ENOMEM= . > > - btrfs_insert_delayed_dir_index_prealloc(): populates the item data, > > inserts into the rb-tree, and reserves metadata space. Cannot fail > > with -ENOMEM since all allocations were done in the prealloc step. > > - btrfs_free_delayed_dir_index_prealloc(): frees pre-allocated > > resources when the caller's btree insertion fails. > >=20 > > The original btrfs_insert_delayed_dir_index() is refactored into a thin > > wrapper that calls the prealloc and commit functions. > >=20 > > This split allows callers to move the fallible memory allocations befor= e > > the point of no return (the DIR_ITEM btree insertion), so that -ENOMEM > > can be returned cleanly without aborting the transaction. > >=20 > > Assisted-by: LLM > > Signed-off-by: Jeff Layton > > --- > > fs/btrfs/delayed-inode.c | 111 +++++++++++++++++++++++++++++++++++++-= --------- > > fs/btrfs/delayed-inode.h | 17 ++++++++ > > 2 files changed, 104 insertions(+), 24 deletions(-) > >=20 > > diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c > > index db2ffab0941a..95d2dca80444 100644 > > --- a/fs/btrfs/delayed-inode.c > > +++ b/fs/btrfs/delayed-inode.c > > @@ -6,6 +6,7 @@ > > =20 > > #include > > #include > > +#include > > #include "ctree.h" > > #include "fs.h" > > #include "messages.h" > > @@ -1469,35 +1470,74 @@ static void btrfs_release_dir_index_item_space(= struct btrfs_trans_handle *trans) > > trans->bytes_reserved -=3D bytes; > > } > > =20 > > -/* Will return 0, -ENOMEM or -EEXIST (index number collision, unexpect= ed). */ > > -int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans, > > - const char *name, int name_len, > > - struct btrfs_inode *dir, > > - const struct btrfs_disk_key *disk_key, u8 flags, > > - u64 index) > > +/* > > + * Pre-allocate a delayed node and delayed item for a dir index insert= ion. > > + * Call this before modifying the btree so that ENOMEM can be returned > > + * before any on-disk state has changed. > > + * > > + * Returns 0 on success, -ENOMEM on allocation failure. > > + */ > > +int btrfs_prealloc_delayed_dir_index(struct btrfs_inode *dir, > > + const char *name, int name_len, > > + struct btrfs_dir_index_prealloc *prealloc) >=20 > We can directly return a btrfs_dir_index_prealloc pointer, which reduce= =20 > the parameter list. >=20 ...but then we'd have to allocate it separately. It's currently allocated on the stack by the caller. I think we ought to keep it this way, but I'm willing to be convinced otherwise. > Otherwise looks good to me. >=20 > Reviewed-by: Qu Wenruo >=20 --=20 Jeff Layton