Messages in this thread | | | Date | Sat, 20 Aug 2011 08:36:43 -0700 | From | Sunil Mushran <> | Subject | Re: [PATCH 1/4] fs: add SEEK_HOLE and SEEK_DATA flags |
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On 08/20/2011 03:03 AM, Marco Stornelli wrote: > Il 20/08/2011 11:41, Marco Stornelli ha scritto: >> Hi, >> >> Il 28/06/2011 17:33, Josef Bacik ha scritto: >>> This just gets us ready to support the SEEK_HOLE and SEEK_DATA flags. >>> Turns out >>> using fiemap in things like cp cause more problems than it solves, so >>> lets try >>> and give userspace an interface that doesn't suck. We need to match >>> solaris >>> here, and the definitions are >>> >>> *o* If /whence/ is SEEK_HOLE, the offset of the start of the >>> next hole greater than or equal to the supplied offset >>> is returned. The definition of a hole is provided near >>> the end of the DESCRIPTION. >>> >>> *o* If /whence/ is SEEK_DATA, the file pointer is set to the >>> start of the next non-hole file region greater than or >>> equal to the supplied offset. >>> >> >> I'm implementing the SEEK_DATA/SEEK_HOLE management for pramfs and I've >> got some doubts about the right behavior: >> >> 1) when we use SEEK_DATA/SEEK_HOLE, the offset used in lseek means >> always the offset from the start of the file, right? >> >> 2) in case of a file with hole at the beginning and data at the end, if >> I do lseek(fd, 0, SEEK_HOLE) I should receive the end of the file >> because the idea is to search the *next* hole and we have always a >> virtual hole at the end of the file, right? > > Just to be precise about this question: the alternative here, it's to > return the same position because we are already in a hole.
Yes, the offset is from the start of the file.
And yes, same offset is ok. I think the word next should be dropped from the definition. It is misleading.
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