punching holes in files
smfrench at gmail.com
Thu Nov 1 19:16:25 GMT 2007
madvise_remove (in Linux) is used to free the backing store associated
with pages (punching a hole in a file). This is one of the vfs
operations that we do not send over the wire to Samba (so this call
would return -ENOSYS locally). Any thoughts on whether this could be
done with an obscure SetFileInfo level or FCNTL or whether it is worth
adding to the CIFS POSIX Extensions?
A second interesting question is whether to implement fallocate over
the wire. sys_fallocate takes a range (and also a flag which
indicates whether to extend the size beyond end of file).
SET_FILE_ALLOCATION_INFO takes a size field rather than a range. For
the case of the range starting at zero, we could simply call Trans2
set pathinfo (or file info) with SET_FILE_ALLOCATION_INFO. Should we
add a CIFS POSIX Extension operation for this too?
By the way it looks like OCFS2 (not just ext4) implement these.
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