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Unix files have (at least) two sizes

(utcc.utoronto.ca)
68 points ingve | 1 comments | 14 Apr 25 10:18 UTC | HN request time: 0.001s | source
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garaetjjte ◴[17 Apr 25 01:28 UTC] No.43712174[source]▶
>However, it does leave us with no way of finding out the logical block size, which we may care about for various reasons

There's SEEK_HOLE and fiemap ioctl.

replies(1): >>43713295 #
1. ryao ◴[17 Apr 25 05:08 UTC] No.43713295[source]▶
SEEK_HOLE would let you find the holes, but not tell you the record size, which is what he wants here. ZFS does not implement .fiemap.

zdb could be used to get this information by inspecting the dataset's object corresponding to the inode number returned by stat, but that is a heavy handed way to find it.

If this exporting this information is important to the original author, I suggest that he file an issue at the OpenZFS bug tracker requesting a way of exporting this information.