On Tue, Jan 17, 2023 at 04:45:05 PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Update the ondisk format documentation to discuss the larger maximum
> extent counts that were added in 2022.
>
Looks good to me.
Reviewed-by: Chandan Babu R <chandan.babu@xxxxxxxxxx>
--
chandan
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> .../allocation_groups.asciidoc | 4 +
> .../XFS_Filesystem_Structure/ondisk_inode.asciidoc | 61 ++++++++++++++++++--
> 2 files changed, 58 insertions(+), 7 deletions(-)
>
>
> diff --git a/design/XFS_Filesystem_Structure/allocation_groups.asciidoc b/design/XFS_Filesystem_Structure/allocation_groups.asciidoc
> index 7ee5d561..c64b4fad 100644
> --- a/design/XFS_Filesystem_Structure/allocation_groups.asciidoc
> +++ b/design/XFS_Filesystem_Structure/allocation_groups.asciidoc
> @@ -454,6 +454,10 @@ xref:Timestamps[timestamps] for more information.
> The filesystem is not in operable condition, and must be run through
> xfs_repair before it can be mounted.
>
> +| +XFS_SB_FEAT_INCOMPAT_NREXT64+ |
> +Large file fork extent counts. This greatly expands the maximum number of
> +space mappings allowed in data and extended attribute file forks.
> +
> |=====
>
> *sb_features_log_incompat*::
> diff --git a/design/XFS_Filesystem_Structure/ondisk_inode.asciidoc b/design/XFS_Filesystem_Structure/ondisk_inode.asciidoc
> index 1922954e..34c06487 100644
> --- a/design/XFS_Filesystem_Structure/ondisk_inode.asciidoc
> +++ b/design/XFS_Filesystem_Structure/ondisk_inode.asciidoc
> @@ -84,14 +84,41 @@ struct xfs_dinode_core {
> __uint32_t di_nlink;
> __uint16_t di_projid;
> __uint16_t di_projid_hi;
> - __uint8_t di_pad[6];
> - __uint16_t di_flushiter;
> + union {
> + /* Number of data fork extents if NREXT64 is set */
> + __be64 di_big_nextents;
> +
> + /* Padding for V3 inodes without NREXT64 set. */
> + __be64 di_v3_pad;
> +
> + /* Padding and inode flush counter for V2 inodes. */
> + struct {
> + __u8 di_v2_pad[6];
> + __be16 di_flushiter;
> + };
> + };
> xfs_timestamp_t di_atime;
> xfs_timestamp_t di_mtime;
> xfs_timestamp_t di_ctime;
> xfs_fsize_t di_size;
> xfs_rfsblock_t di_nblocks;
> xfs_extlen_t di_extsize;
> + union {
> + /*
> + * For V2 inodes and V3 inodes without NREXT64 set, this
> + * is the number of data and attr fork extents.
> + */
> + struct {
> + __be32 di_nextents;
> + __be16 di_anextents;
> + } __packed;
> +
> + /* Number of attr fork extents if NREXT64 is set. */
> + struct {
> + __be32 di_big_anextents;
> + __be16 di_nrext64_pad;
> + } __packed;
> + } __packed;
> xfs_extnum_t di_nextents;
> xfs_aextnum_t di_anextents;
> __uint8_t di_forkoff;
> @@ -162,7 +189,7 @@ When the number exceeds 65535, the inode is converted to v2 and the link count
> is stored in +di_nlink+.
>
> *di_uid*::
> -Specifies the owner's UID of the inode.
> +Specifies the owner's UID of the inode.
>
> *di_gid*::
> Specifies the owner's GID of the inode.
> @@ -181,10 +208,17 @@ Specifies the high 16 bits of the owner's project ID in v2 inodes, if the
> +XFS_SB_VERSION2_PROJID32BIT+ feature is set; and zero otherwise.
>
> *di_pad[6]*::
> -Reserved, must be zero.
> +Reserved, must be zero. Only exists for v2 inodes.
>
> *di_flushiter*::
> -Incremented on flush.
> +Incremented on flush. Only exists for v2 inodes.
> +
> +*di_v3_pad*::
> +Must be zero for v3 inodes without the NREXT64 flag set.
> +
> +*di_big_nextents*::
> +Specifies the number of data extents associated with this inode if the NREXT64
> +flag is set. This allows for up to 2^48^ - 1 extent mappings.
>
> *di_atime*::
>
> @@ -231,10 +265,19 @@ file is written to beyond allocated space, XFS will attempt to allocate
> additional disk space based on this value.
>
> *di_nextents*::
> -Specifies the number of data extents associated with this inode.
> +Specifies the number of data extents associated with this inode if the NREXT64
> +flag is not set. Supports up to 2^31^ - 1 extents.
>
> *di_anextents*::
> -Specifies the number of extended attribute extents associated with this inode.
> +Specifies the number of extended attribute extents associated with this inode
> +if the NREXT64 flag is not set. Supports up to 2^15^ - 1 extents.
> +
> +*di_big_anextents*::
> +Specifies the number of extended attribute extents associated with this inode
> +if the NREXT64 flag is set. Supports up to 2^32^ - 1 extents.
> +
> +*di_nrext64_pad*::
> +Must be zero if the NREXT64 flag is set.
>
> *di_forkoff*::
> Specifies the offset into the inode's literal area where the extended attribute
> @@ -336,6 +379,10 @@ This inode shares (or has shared) data blocks with another inode.
> For files, this is the extent size hint for copy on write operations; see
> +di_cowextsize+ for details. For directories, the value in +di_cowextsize+
> will be copied to all newly created files and directories.
> +| +XFS_DIFLAG2_NREXT64+ |
> +Files with this flag set may have up to (2^48^ - 1) extents mapped to the data
> +fork and up to (2^32^ - 1) extents mapped to the attribute fork. This flag
> +requires the +XFS_SB_FEAT_INCOMPAT_NREXT64+ feature to be enabled.
> |=====
>
> *di_cowextsize*::
