bbdc6ae495
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. 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(). Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #168 |
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