From bd6ae049b7be4785082e5c3c0a80e8c9e3ff2fc6 Mon Sep 17 00:00:00 2001 From: Konstantin Komarov Date: Fri, 9 Sep 2022 19:12:31 +0300 Subject: [PATCH] fs/ntfs3: Add comments about cluster size This commit adds additional info about CONFIG_NTFS3_64BIT_CLUSTER Signed-off-by: Konstantin Komarov --- fs/ntfs3/frecord.c | 2 +- fs/ntfs3/record.c | 4 ++++ fs/ntfs3/super.c | 24 ++++++++++++++++++++++++ 3 files changed, 29 insertions(+), 1 deletion(-) diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c index 381a38a0..b752d83 100644 --- a/fs/ntfs3/frecord.c +++ b/fs/ntfs3/frecord.c @@ -557,7 +557,7 @@ static int ni_repack(struct ntfs_inode *ni) } if (!mi_p) { - /* Do not try if not enogh free space. */ + /* Do not try if not enough free space. */ if (le32_to_cpu(mi->mrec->used) + 8 >= rs) continue; diff --git a/fs/ntfs3/record.c b/fs/ntfs3/record.c index 7d2fac5..c8741cf 100644 --- a/fs/ntfs3/record.c +++ b/fs/ntfs3/record.c @@ -537,6 +537,10 @@ bool mi_resize_attr(struct mft_inode *mi, struct ATTRIB *attr, int bytes) return true; } +/* + * Pack runs in MFT record. + * If failed record is not changed. + */ int mi_pack_runs(struct mft_inode *mi, struct ATTRIB *attr, struct runs_tree *run, CLST len) { diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index 47012c9..683687c 100644 --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -21,6 +21,30 @@ * https://docs.microsoft.com/en-us/windows/wsl/file-permissions * It stores uid/gid/mode/dev in xattr * + * ntfs allows up to 2^64 clusters per volume. + * It means you should use 64 bits lcn to operate with ntfs. + * Implementation of ntfs.sys uses only 32 bits lcn. + * Default ntfs3 uses 32 bits lcn too. + * ntfs3 built with CONFIG_NTFS3_64BIT_CLUSTER (ntfs3_64) uses 64 bits per lcn. + * + * + * ntfs limits, cluster size is 4K (2^12) + * ----------------------------------------------------------------------------- + * | Volume size | Clusters | ntfs.sys | ntfs3 | ntfs3_64 | mkntfs | chkdsk | + * ----------------------------------------------------------------------------- + * | < 16T, 2^44 | < 2^32 | yes | yes | yes | yes | yes | + * | > 16T, 2^44 | > 2^32 | no | no | yes | yes | yes | + * ----------------------------------------------------------|------------------ + * + * To mount large volumes as ntfs one should use large cluster size (up to 2M) + * The maximum volume size in this case is 2^32 * 2^21 = 2^53 = 8P + * + * ntfs limits, cluster size is 2M (2^31) + * ----------------------------------------------------------------------------- + * | < 8P, 2^54 | < 2^32 | yes | yes | yes | yes | yes | + * | > 8P, 2^54 | > 2^32 | no | no | yes | yes | yes | + * ----------------------------------------------------------|------------------ + * */ #include -- 2.7.4