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/*
* XFS preallocation support module.
*
* Copyright (c) James Peach 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "system/filesys.h"
#include "smbd/smbd.h"
/* Extent preallocation module.
*
* The purpose of this module is to preallocate space on the filesystem when
* we have a good idea of how large files are supposed to be. This lets writes
* proceed without having to allocate new extents and results in better file
* layouts on disk.
*
* Currently only implemented for XFS. This module is based on an original idea
* and implementation by Sebastian Brings.
*
* Tunables.
*
* prealloc: <ext> Number of bytes to preallocate for a file with
* the matching extension.
* prealloc:debug Debug level at which to emit messages.
*
* Example.
*
* prealloc:mpeg = 500M # Preallocate *.mpeg to 500 MiB.
*/
#ifdef HAVE_XFS_LIBXFS_H
#include <xfs/libxfs.h>
#define lock_type xfs_flock64_t
#else
#define lock_type struct flock64
#endif
#define MODULE "prealloc"
static int module_debug;
static int preallocate_space(int fd, off_t size)
{
int err;
lock_type fl = {0};
if (size <= 0) {
return 0;
}
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = size;
/* IMPORTANT: We use RESVSP because we want the extents to be
* allocated, but we don't want the allocation to show up in
* st_size or persist after the close(2).
*/
#if defined(XFS_IOC_RESVSP64)
/* On Linux this comes in via libxfs.h. */
err = xfsctl(NULL, fd, XFS_IOC_RESVSP64, &fl);
#elif defined(F_RESVSP64)
/* On IRIX, this comes from fcntl.h. */
err = fcntl(fd, F_RESVSP64, &fl);
#else
err = -1;
errno = ENOSYS;
#endif
if (err) {
DEBUG(module_debug,
("%s: preallocate failed on fd=%d size=%lld: %s\n",
MODULE, fd, (long long)size, strerror(errno)));
}
return err;
}
static int prealloc_connect(
struct vfs_handle_struct * handle,
const char * service,
const char * user)
{
int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
if (ret < 0) {
return ret;
}
module_debug = lp_parm_int(SNUM(handle->conn),
MODULE, "debug", 100);
return 0;
}
static int prealloc_openat(struct vfs_handle_struct* handle,
const struct files_struct *dirfsp,
const struct smb_filename *smb_fname,
files_struct *fsp,
const struct vfs_open_how *how)
{
int fd;
off_t size = 0;
const char * dot;
char fext[10];
if (!(how->flags & (O_CREAT|O_TRUNC))) {
/* Caller is not intending to rewrite the file. Let's not mess
* with the allocation in this case.
*/
goto normal_open;
}
*fext = '\0';
dot = strrchr(smb_fname->base_name, '.');
if (dot && *++dot) {
if (strlen(dot) < sizeof(fext)) {
bool ok;
strncpy(fext, dot, sizeof(fext));
ok = strlower_m(fext);
if (!ok);
goto normal_open;
}
}
}
if (*fext == '\0') {
goto normal_open;
}
/* Syntax for specifying preallocation size is:
* MODULE: <extension> = <size>
* where
* <extension> is the file extension in lower case
* <size> is a size like 10, 10K, 10M
*/
size = conv_str_size(lp_parm_const_string(SNUM(handle->conn), MODULE,
fext, NULL));
if (size <= 0) {
/* No need to preallocate this file. */
goto normal_open;
}
fd = SMB_VFS_NEXT_OPENAT(handle, dirfsp, smb_fname, fsp, how);
if (fd < 0) {
return fd;
}
/* Preallocate only if the file is being created or replaced. Note that
* Samba won't ever pass down O_TRUNC, which is why we have to handle
* truncate calls specially.
*/
if ((how->flags & O_CREAT) || (how->flags & O_TRUNC)) {
off_t * psize;
psize = VFS_ADD_FSP_EXTENSION(handle, fsp, off_t, NULL);
if (psize == NULL || *psize == -1) {
return fd;
}
DEBUG(module_debug,
("%s: preallocating %s (fd=%d) to %lld bytes\n",
MODULE, smb_fname_str_dbg(smb_fname), fd,
(long long)size));
*psize = size;
if (preallocate_space(fd, *psize) < 0) {
VFS_REMOVE_FSP_EXTENSION(handle, fsp);
}
}
return fd;
normal_open:
/* We are not creating or replacing a file. Skip the
* preallocation.
*/
DEBUG(module_debug, ("%s: skipping preallocation for %s\n",
MODULE, smb_fname_str_dbg(smb_fname)));
return SMB_VFS_NEXT_OPENAT(handle, dirfsp, smb_fname, fsp, how);
}
static int prealloc_ftruncate(vfs_handle_struct * handle,
files_struct * fsp,
off_t offset)
{
off_t *psize;
int ret = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, offset);
/* Maintain the allocated space even in the face of truncates. */
if ((psize = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
preallocate_space(fsp_get_io_fd(fsp), *psize);
}
return ret;
}
static struct vfs_fn_pointers prealloc_fns = {
.openat_fn = prealloc_openat,
.ftruncate_fn = prealloc_ftruncate,
.connect_fn = prealloc_connect,
};
static_decl_vfs;
NTSTATUS vfs_prealloc_init(TALLOC_CTX *ctx)
{
return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
MODULE, &prealloc_fns);
}
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