diff options
Diffstat (limited to 'source3/modules/vfs_prealloc.c')
| -rw-r--r-- | source3/modules/vfs_prealloc.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/source3/modules/vfs_prealloc.c b/source3/modules/vfs_prealloc.c new file mode 100644 index 0000000..51e9ad0 --- /dev/null +++ b/source3/modules/vfs_prealloc.c @@ -0,0 +1,222 @@ +/* + * 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); +} |