| Message ID | 20231204234615.3592624-1-drosen@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [f2fs-dev,v2] f2fs: Restrict max filesize for 16K f2fs | expand |
On Mon, Dec 04, 2023 at 03:46:15PM -0800, Daniel Rosenberg via Linux-f2fs-devel wrote: > Blocks are tracked by u32, so the max permitted filesize is > U32_MAX * BLOCK_SIZE. Additionally, in order to support crypto data unit > sizes of 4K with a 16K block size with IV_INO_LBLK_{32,63}, we must {32,63} should be {32,64} > + /* > + * For compatibility with FSCRYPT_POLICY_IV_INO_LBLK_{64,32} with a > + * 4K crypto data unit, we must restrict the max filesize to what can > + * fit within U32_MAX data units. FSCRYPT_POLICY_IV_INO_LBLK_{64,32} should be FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{64,32} > + * > + * Since the blocksize must currently be equal to the page size, > + * we can use a constant for that. Note if this is not the case > + * in the future that inode is NULL while setting up the superblock. I'm not sure what the last sentence is trying to say. > + */ > + > + result = min(result, ((loff_t) U32_MAX * 4096) >> F2FS_BLKSIZE_BITS); Is it intentional that this is off by 1? If indices can be up to U32_MAX, then the maximum size is U32_MAX + 1. It's not a bad idea to go with the lower size, so that max_index + 1 does not overflow. But that's not what the explanation says, so this seems to be accidental. - Eric
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 033af907c3b1..18a2189a0dc4 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3364,6 +3364,18 @@ loff_t max_file_blocks(struct inode *inode) leaf_count *= NIDS_PER_BLOCK; result += leaf_count; + /* + * For compatibility with FSCRYPT_POLICY_IV_INO_LBLK_{64,32} with a + * 4K crypto data unit, we must restrict the max filesize to what can + * fit within U32_MAX data units. + * + * Since the blocksize must currently be equal to the page size, + * we can use a constant for that. Note if this is not the case + * in the future that inode is NULL while setting up the superblock. + */ + + result = min(result, ((loff_t) U32_MAX * 4096) >> F2FS_BLKSIZE_BITS); + return result; }
Blocks are tracked by u32, so the max permitted filesize is U32_MAX * BLOCK_SIZE. Additionally, in order to support crypto data unit sizes of 4K with a 16K block size with IV_INO_LBLK_{32,63}, we must further restrict max filesize to U32_MAX * 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@google.com> --- fs/f2fs/super.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) base-commit: d346fa09abff46988de9267b67b6900d9913d5a2