linux-kernel - [PATCH v3] f2fs: Restrict max filesize for 16K f2fs

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Message-ID: <20231205023801.3669458-1-drosen@google.com>
Date:   Mon,  4 Dec 2023 18:38:01 -0800
From:   Daniel Rosenberg <drosen@...gle.com>
To:     linux-f2fs-devel@...ts.sourceforge.net
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        Daniel Rosenberg <drosen@...gle.com>
Subject: [PATCH v3] f2fs: Restrict max filesize for 16K f2fs

Blocks are tracked by u32, so the max permitted filesize is
(U32_MAX + 1) * BLOCK_SIZE. Additionally, in order to support crypto
data unit sizes of 4K with a 16K block with IV_INO_LBLK_{32,64}, we must
further restrict max filesize to (U32_MAX + 1) * 4096. This does not
affect 4K blocksize f2fs as the natural limit for files are well below
that.

Fixes: d7e9a9037de2 ("f2fs: Support Block Size == Page Size")
Signed-off-by: Daniel Rosenberg <drosen@...gle.com>
---
 fs/f2fs/super.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 033af907c3b1..5dfbc6b4c0ac 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3364,6 +3364,14 @@ loff_t max_file_blocks(struct inode *inode)
 	leaf_count *= NIDS_PER_BLOCK;
 	result += leaf_count;
 
+	/*
+	 * For compatibility with FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{64,32} with
+	 * a 4K crypto data unit, we must restrict the max filesize to what can
+	 * fit within U32_MAX + 1 data units.
+	 */
+
+	result = min(result, (((loff_t)U32_MAX + 1) * 4096) >> F2FS_BLKSIZE_BITS);
+
 	return result;
 }
 

base-commit: d346fa09abff46988de9267b67b6900d9913d5a2
-- 
2.43.0.rc2.451.g8631bc7472-goog