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Add interface for file hole punching #168
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This adds an interface to "punch holes" (deallocate space) in VFS files. The interface is identical to the Solaris VOP_SPACE interface. This interface is necessary for TRIM support on file vdevs. This is implemented using Linux fallocate(FALLOC_FL_PUNCH_HOLE), which was introduced in 2.6.38. For a brief time before 2.6.38 this was done using the truncate_range inode operation, which was quickly deprecated. This patch only supports FALLOC_FL_PUNCH_HOLE.
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@dechamps I'm going to hold of merging this until -rc12 since I want to get something known stable tagged soonish. |
Currently, VOP_SPACE() returns a negative error code in some cases. It shouldn't. This patch fixes that.
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Don't merge this just yet, I'll be adding |
Reverts a remarkably dumb part of 0c0cb0d. "Yo Dawg, we heard you like configure checks so we put a #define in your #define so you can #ifdef while you #ifdef"
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Okay, this is ready for merging now. Just squash everything together and you're good to go. |
This adds support for the truncate_range() inode operation to VOP_SPACE() for file hole punching. This API is deprecated and removed in 3.5, so it's only useful for old kernels.
On tmpfs, the truncate_range() inode operation translates to shmem_truncate_range(). Unfortunately, this function expects the end offset to be inclusive and aligned to the end of a page. If it is not, the kernel will stop with a BUG_ON(). This patch fixes the issue by adapting to the constraints set forth by shmem_truncate_range().
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@behlendorf: now would probably be a good time to merge this. |
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Yup. I was working on pulling it in yesterday I'll get it finished today. |
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This adds an interface to "punch holes" (deallocate space) in VFS files. The interface is identical to the Solaris
VOP_SPACEinterface. This interface is necessary for TRIM support on file vdevs (see openzfs/zfs#924).This is implemented using Linux
fallocate(FALLOC_FL_PUNCH_HOLE), which was introduced in 2.6.38. For a brief time before 2.6.38 this was done using thetruncate_rangeinode operation, which was quickly deprecated. This patch only supportsFALLOC_FL_PUNCH_HOLE.@behlendorf: like the previous patch, you can either wait for ZFS TRIM support to be finished or you can merge this now. Your call.