On 12/17/13, 2:17 AM, Andreas Dilger wrote: > The mke2fs(8) man page was updated in 4727c67dc2, but needs some > more clear descriptions for extra_isize and metadta_csum features. > The uninit_bg feature is supported by all ext4-capable kernels, > and does have a slow e2fsck pass for newly-formatted filesystems, > so remove the caveat. Looks ok to me, but I think there's still one thing missing; it mentions metadata checksums but nothing in the manpage says how to turn those on, AFAICT: $ grep -i2 "checksum\|csum\|crc" misc/mke2fs.8 .B uninit_bg Create a filesystem without initializing all of the block groups. This feature also enables checksums and highest-inode-used statistics in each blockgroup. This feature can speed up filesystem creation time noticeably (if lazy_itable_init is (maybe I'm dense & missing it?) -Eric > Signed-off-by: Andreas Dilger <adilger@xxxxxxxxx> > --- > misc/mke2fs.8.in | 36 ++++++++++++++++++++++-------------- > 1 files changed, 22 insertions(+), 14 deletions(-) > > diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in > index df244de..4486014 100644 > --- a/misc/mke2fs.8.in > +++ b/misc/mke2fs.8.in > @@ -210,8 +210,8 @@ in earlier versions of > .BR mke2fs . > The > .B \-R > -option is still accepted for backwards compatibility. The > -following extended options are supported: > +option is still accepted for backwards compatibility, but is deprecated. > +The following extended options are supported: > .RS 1.2i > .TP > .BI mmp_update_interval= interval > @@ -548,7 +548,7 @@ of e2fsprogs will not support file systems with this feature enabled. > .TP > .B bigalloc > .br > -This feature enables clustered allocation, so that the unit of > +This feature enables clustered block allocation, so that the unit of > allocation is a power of two number of blocks. That is, each bit in the > what had traditionally been known as the block allocation bitmap now > indicates whether a cluster is in use or not, where a cluster is by > @@ -570,7 +570,7 @@ features be enabled. > .TP > .B dir_index > .br > -Use hashed b-trees to speed up lookups in large directories. > +Use hashed b-trees to speed up name lookups in large directories. > .TP > .B dir_nlink > .br > @@ -590,8 +590,15 @@ historical/backwards compatibility reasons.) > .TP > .B extra_isize > .br > -This feature enables storage of nanosecond timestamps and creation > -time, if the inode size is larger than 256 bytes or larger. > +This feature reserves a specific amount of space in each inode for > +extended metadata such as nanosecond timestamps and file creation time, > +even if the current kernel does not current need to reserve this much > +space. Without this feature, the kernel will reserve the amount of > +space for features currently it currently needs, and the rest may be > +consumed by extended attributes. > + > +For this feature to be useful the inode size must be 256 bytes in size > +or larger. > .TP > .B ext_attr > .br > @@ -649,10 +656,16 @@ set this feature automatically when a file > 2GiB is created.) > .\" .TP > .\" .B metadata_csum > .\" .br > -.\" Filesystem supports metadata checksumming. This feature enables a > -.\" superset of the functionality of the > +.\" Filesystem supports metadata checksumming. This feature stores > +.\" checksums for all of the filesystem metadata (superblock, group > +.\" descriptor blocks, inode and block bitmaps, directories, and > +.\" extent tree blocks). The checksum algorithm used for the metadata > +.\" blocks is different than the one used for group descriptors with the > .\" .B uninit_bg > -.\" feature. > +.\" feature, these two features are incompatible and > +.\" .B metadata_csum > +.\" will be used preferentially instead of > +.\" .BR uninit_bg . > .\" .br > .\" .B Future feature, available in e2fsprogs 1.43-WIP > .TP > @@ -719,11 +732,6 @@ and keep a high watermark for the unused inodes in a filesystem, to reduce > .BR e2fsck (8) > time. The result is that it can speed up filesystem creation time noticeably > (if lazy_itable_init is enabled). > -.IP > -This first e2fsck run after enabling this feature will take the > -full time, but subsequent e2fsck runs will take only a fraction of the > -original time, depending on how full the file system is. > -It is only supported by the ext4 filesystem in recent Linux kernels. > .RE > .TP > .B \-q > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
