Messages in this thread | | | Date | Thu, 24 Nov 2011 11:22:34 +0800 | From | Cong Wang <> | Subject | Re: [V3 PATCH 1/2] tmpfs: add fallocate support |
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于 2011年11月24日 11:01, KAMEZAWA Hiroyuki 写道: > On Wed, 23 Nov 2011 21:46:39 -0500 > KOSAKI Motohiro<kosaki.motohiro@jp.fujitsu.com> wrote: > >>>> + while (index< end) { >>>> + ret = shmem_getpage(inode, index,&page, SGP_WRITE, NULL); >>> >>> If the 'page' for index exists before this call, this will return the page without >>> allocaton. >>> >>> Then, the page may not be zero-cleared. I think the page should be zero-cleared. >> >> No. fallocate shouldn't destroy existing data. It only ensure >> subsequent file access don't make ENOSPC error. >> > FALLOC_FL_KEEP_SIZE > This flag allocates and initializes to zero the disk space > within the range specified by offset and len. .... > > just manual is unclear ? it seems that the range [offset, offset+len) is > zero cleared after the call.
I think we should fix the man page, because at least ext4 doesn't clear the original contents,
% echo hi > /tmp/foobar % fallocate -n -l 1 -o 10 /tmp/foobar % hexdump -Cv /tmp/foobar 00000000 68 69 0a |hi.| 00000003 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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