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Implement the truncate_range() inode operation.

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This operation allows "hole punching" in ZFS files. On Solaris this
is done via the vop_space() system call, which maps to the zfs_space()
function. So we just need to write zpl_truncate_range() as a wrapper
around zfs_space().

Note that this only works for regular files, not ZVOLs.

This is currently an insecure implementation without permission
checking, although this isn't that big of a deal since truncate_range()
isn't even callable from userspace.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #334
This commit is contained in:
Etienne Dechamps 2011-09-01 13:59:41 +02:00 committed by Brian Behlendorf
parent 93648f314c
commit 5cb63a57f8
1 changed files with 28 additions and 0 deletions
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28
module/zfs/zpl_inode.c
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@ -315,6 +315,33 @@ zpl_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
return (error);
}
static void
zpl_truncate_range(struct inode* ip, loff_t start, loff_t end)
{
cred_t *cr = CRED();
flock64_t bf;
ASSERT3S(start, <=, end);
/*
* zfs_freesp() will interpret (len == 0) as meaning "truncate until
* the end of the file". We don't want that.
*/
if (start == end)
return;
crhold(cr);
bf.l_type = F_WRLCK;
bf.l_whence = 0;
bf.l_start = start;
bf.l_len = end - start;
bf.l_pid = 0;
zfs_space(ip, F_FREESP, &bf, FWRITE, start, cr);
crfree(cr);
}
const struct inode_operations zpl_inode_operations = {
.create = zpl_create,
.link = zpl_link,
@ -330,6 +357,7 @@ const struct inode_operations zpl_inode_operations = {
.getxattr = generic_getxattr,
.removexattr = generic_removexattr,
.listxattr = zpl_xattr_list,
.truncate_range = zpl_truncate_range,
};
const struct inode_operations zpl_dir_inode_operations = {