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samba-mirror/source3/smbd/fileio.c

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/*
Unix SMB/Netbios implementation.
Version 1.9.
read/write to a files_struct
Copyright (C) Andrew Tridgell 1992-1998
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 2 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
extern int DEBUGLEVEL;
static BOOL setup_write_cache(files_struct *, SMB_OFF_T);
/****************************************************************************
seek a file. Try to avoid the seek if possible
****************************************************************************/
SMB_OFF_T seek_file(files_struct *fsp,SMB_OFF_T pos)
{
SMB_OFF_T offset = 0;
SMB_OFF_T seek_ret;
if (fsp->print_file && lp_postscript(fsp->conn->service))
offset = 3;
seek_ret = fsp->conn->vfs_ops.lseek(fsp->fd_ptr->fd,pos+offset,SEEK_SET);
/*
* We want to maintain the fiction that we can seek
* on a fifo for file system purposes. This allows
* people to set up UNIX fifo's that feed data to Windows
* applications. JRA.
*/
if((seek_ret == -1) && (errno == ESPIPE)) {
seek_ret = pos+offset;
errno = 0;
}
if((seek_ret == -1) || (seek_ret != pos+offset)) {
DEBUG(0,("seek_file: sys_lseek failed. Error was %s\n", strerror(errno) ));
fsp->pos = -1;
return -1;
}
fsp->pos = seek_ret - offset;
DEBUG(10,("seek_file: requested pos = %.0f, new pos = %.0f\n",
(double)(pos+offset), (double)fsp->pos ));
return(fsp->pos);
}
/****************************************************************************
Read from write cache if we can.
****************************************************************************/
static unsigned int cache_read_hits;
BOOL read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
{
write_cache *wcp = fsp->wcp;
if(!wcp)
return False;
if(n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size)
return False;
memcpy(data, wcp->data + (pos - wcp->offset), n);
cache_read_hits++;
return True;
}
/****************************************************************************
read from a file
****************************************************************************/
ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
{
ssize_t ret=0,readret;
#if USE_READ_PREDICTION
if (!fsp->can_write) {
ret = read_predict(fsp->fd_ptr->fd,pos,data,NULL,n);
data += ret;
n -= ret;
pos += ret;
}
#endif
/*
* Serve from write cache if we can.
*/
if(read_from_write_cache(fsp, data, pos, n))
return n;
flush_write_cache(fsp, READ_FLUSH);
if (seek_file(fsp,pos) == -1) {
DEBUG(3,("read_file: Failed to seek to %.0f\n",(double)pos));
return(ret);
}
if (n > 0) {
readret = fsp->conn->vfs_ops.read(fsp->fd_ptr->fd,data,n);
if (readret > 0) ret += readret;
}
return(ret);
}
/* Write cache static counters. */
static unsigned int abutted_writes;
static unsigned int total_writes;
static unsigned int non_oplock_writes;
static unsigned int direct_writes;
static unsigned int init_writes;
static unsigned int flushed_writes;
static unsigned int num_perfect_writes;
static unsigned int flush_reasons[NUM_FLUSH_REASONS];
/* how many write cache buffers have been allocated */
static unsigned int allocated_write_caches;
static unsigned int num_write_caches;
/****************************************************************************
*Really* write to a file
****************************************************************************/
static ssize_t real_write_file(files_struct *fsp,char *data,SMB_OFF_T pos, size_t n)
{
if ((pos != -1) && (seek_file(fsp,pos) == -1))
return -1;
return write_data(fsp->fd_ptr->fd,data,n);
}
/****************************************************************************
write to a file
****************************************************************************/
ssize_t write_file(files_struct *fsp, char *data, SMB_OFF_T pos, size_t n)
{
write_cache *wcp = fsp->wcp;
ssize_t total_written = 0;
int write_path = -1;
if (!fsp->can_write) {
errno = EPERM;
return(0);
}
if (!fsp->modified) {
SMB_STRUCT_STAT st;
fsp->modified = True;
if (fsp->conn->vfs_ops.fstat(fsp->fd_ptr->fd,&st) == 0) {
int dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
if (MAP_ARCHIVE(fsp->conn) && !IS_DOS_ARCHIVE(dosmode)) {
file_chmod(fsp->conn,fsp->fsp_name,dosmode | aARCH,&st);
}
/*
* If this is the first write and we have an exclusive oplock then setup
* the write cache.
*/
if ((fsp->oplock_type == EXCLUSIVE_OPLOCK) && !wcp) {
setup_write_cache(fsp, st.st_size);
wcp = fsp->wcp;
}
}
}
total_writes++;
if (!fsp->oplock_type) {
non_oplock_writes++;
}
/*
* If this file is level II oplocked then we need
* to grab the shared memory lock and inform all
* other files with a level II lock that they need
* to flush their read caches. We keep the lock over
* the shared memory area whilst doing this.
*/
if (LEVEL_II_OPLOCK_TYPE(fsp->oplock_type)) {
SMB_DEV_T dev = fsp->fd_ptr->dev;
SMB_INO_T inode = fsp->fd_ptr->inode;
share_mode_entry *share_list = NULL;
pid_t pid = getpid();
int token = -1;
int num_share_modes = 0;
int i;
if (lock_share_entry(fsp->conn, dev, inode) == False) {
DEBUG(0,("write_file: failed to lock share mode entry for file %s.\n", fsp->fsp_name ));
}
num_share_modes = get_share_modes(fsp->conn, dev, inode, &share_list);
for(i = 0; i < num_share_modes; i++) {
share_mode_entry *share_entry = &share_list[i];
/*
* As there could have been multiple writes waiting at the lock_share_entry
* gate we may not be the first to enter. Hence the state of the op_types
* in the share mode entries may be partly NO_OPLOCK and partly LEVEL_II
* oplock. It will do no harm to re-send break messages to those smbd's
* that are still waiting their turn to remove their LEVEL_II state, and
* also no harm to ignore existing NO_OPLOCK states. JRA.
*/
if (share_entry->op_type == NO_OPLOCK)
continue;
/* Paranoia .... */
if (EXCLUSIVE_OPLOCK_TYPE(share_entry->op_type)) {
DEBUG(0,("write_file: PANIC. share mode entry %d is an exlusive oplock !\n", i ));
abort();
}
/*
* Check if this is a file we have open (including the
* file we've been called to do write_file on. If so
* then break it directly without releasing the lock.
*/
if (pid == share_entry->pid) {
files_struct *new_fsp = file_find_dit(dev, inode, &share_entry->time);
/* Paranoia check... */
if(new_fsp == NULL) {
DEBUG(0,("write_file: PANIC. share mode entry %d is not a local file !\n", i ));
abort();
}
oplock_break_level2(new_fsp, True, token);
} else {
/*
* This is a remote file and so we send an asynchronous
* message.
*/
request_oplock_break(share_entry, dev, inode);
}
}
free((char *)share_list);
unlock_share_entry(fsp->conn, dev, inode);
}
/* Paranoia check... */
if (LEVEL_II_OPLOCK_TYPE(fsp->oplock_type)) {
DEBUG(0,("write_file: PANIC. File %s still has a level II oplock.\n", fsp->fsp_name));
abort();
}
if (total_writes % 500 == 0) {
DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u flushes=%u total=%u \
nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
init_writes, abutted_writes, flushed_writes, total_writes, non_oplock_writes,
allocated_write_caches,
num_write_caches, direct_writes, num_perfect_writes, cache_read_hits ));
DEBUG(3,("WRITECACHE: SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
flush_reasons[SEEK_FLUSH],
flush_reasons[READ_FLUSH],
flush_reasons[WRITE_FLUSH],
flush_reasons[READRAW_FLUSH],
flush_reasons[OPLOCK_RELEASE_FLUSH],
flush_reasons[CLOSE_FLUSH],
flush_reasons[SYNC_FLUSH] ));
}
if(!wcp) {
direct_writes++;
return real_write_file(fsp, data, pos, n);
}
DEBUG(9,("write_file(fd=%d pos=%d size=%d) wofs=%d wsize=%d\n",
fsp->fd_ptr->fd, (int)pos, (int)n, (int)wcp->offset, (int)wcp->data_size));
/*
* If we have active cache and it isn't contiguous then we flush.
* NOTE: There is a small problem with running out of disk ....
*/
if (wcp->data_size) {
BOOL cache_flush_needed = False;
if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
/*
* Start of write overlaps or abutts the existing data.
*/
size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
memcpy(wcp->data + (pos - wcp->offset), data, data_used);
/*
* Update the current buffer size with the new data.
*/
if(pos + data_used > wcp->offset + wcp->data_size)
wcp->data_size = pos + data_used - wcp->offset;
/*
* If we used all the data then
* return here.
*/
if(n == data_used)
return n;
else
cache_flush_needed = True;
/*
* Move the start of data forward by the amount used,
* cut down the amount left by the same amount.
*/
data += data_used;
pos += data_used;
n -= data_used;
abutted_writes++;
total_written = data_used;
write_path = 1;
} else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
(pos + n <= wcp->offset + wcp->alloc_size)) {
/*
* End of write overlaps the existing data.
*/
size_t data_used = pos + n - wcp->offset;
memcpy(wcp->data, data + n - data_used, data_used);
/*
* Update the current buffer size with the new data.
*/
if(pos + n > wcp->offset + wcp->data_size)
wcp->data_size = pos + n - wcp->offset;
/*
* We don't need to move the start of data, but we
* cut down the amount left by the amount used.
*/
n -= data_used;
/*
* We cannot have used all the data here.
*/
cache_flush_needed = True;
abutted_writes++;
total_written = data_used;
write_path = 2;
} else if ( (pos >= wcp->file_size) &&
(pos > wcp->offset + wcp->data_size) &&
(pos < wcp->offset + wcp->alloc_size) ) {
/*
* Non-contiguous write part of which fits within
* the cache buffer and is extending the file.
*/
size_t data_used;
if(pos + n <= wcp->offset + wcp->alloc_size)
data_used = n;
else
data_used = wcp->offset + wcp->alloc_size - pos;
/*
* Fill in the non-continuous area with zeros.
*/
memset(wcp->data + wcp->data_size, '\0',
pos - (wcp->offset + wcp->data_size) );
memcpy(wcp->data + (pos - wcp->offset), data, data_used);
/*
* Update the current buffer size with the new data.
*/
if(pos + data_used > wcp->offset + wcp->data_size)
wcp->data_size = pos + data_used - wcp->offset;
/*
* Update the known file length.
*/
wcp->file_size = wcp->offset + wcp->data_size;
#if 0
if (set_filelen(fsp->fd_ptr->fd, wcp->file_size) == -1) {
DEBUG(0,("write_file: error %s in setting file to length %.0f\n",
strerror(errno), (double)wcp->file_size ));
return -1;
}
#endif
/*
* If we used all the data then
* return here.
*/
if(n == data_used)
return n;
else
cache_flush_needed = True;
/*
* Move the start of data forward by the amount used,
* cut down the amount left by the same amount.
*/
data += data_used;
pos += data_used;
n -= data_used;
abutted_writes++;
total_written = data_used;
write_path = 3;
} else {
/*
* Write is bigger than buffer, or there is no overlap on the
* low or high ends.
*/
DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
len = %u\n",fsp->fd_ptr->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
/*
* Update the file size if needed.
*/
if(pos + n > wcp->file_size)
wcp->file_size = pos + n;
/*
* If write would fit in the cache, and is larger than
* the data already in the cache, flush the cache and
* preferentially copy the data new data into it. Otherwise
* just write the data directly.
*/
if ( n <= wcp->alloc_size && n > wcp->data_size) {
cache_flush_needed = True;
} else {
direct_writes++;
return real_write_file(fsp, data, pos, n);
}
write_path = 4;
}
if(wcp->data_size > wcp->file_size)
wcp->file_size = wcp->data_size;
if (cache_flush_needed) {
flushed_writes++;
DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
write_path, fsp->fd_ptr->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
(double)wcp->offset, (unsigned int)wcp->data_size ));
flush_write_cache(fsp, WRITE_FLUSH);
}
}
/*
* If the write request is bigger than the cache
* size, write it all out.
*/
if (n > wcp->alloc_size ) {
if(real_write_file(fsp, data, pos, n) == -1)
return -1;
direct_writes++;
return total_written + n;
}
/*
* If there's any data left, cache it.
*/
if (n) {
if (wcp->data_size) {
abutted_writes++;
DEBUG(9,("abutted write (%u)\n", abutted_writes));
} else {
init_writes++;
}
memcpy(wcp->data+wcp->data_size, data, n);
if (wcp->data_size == 0) {
wcp->offset = pos;
num_write_caches++;
}
wcp->data_size += n;
DEBUG(9,("cache return %u\n", (unsigned int)n));
total_written += n;
return total_written; /* .... that's a write :) */
}
return total_written;
}
/****************************************************************************
Delete the write cache structure.
****************************************************************************/
void delete_write_cache(files_struct *fsp)
{
write_cache *wcp;
if(!fsp)
return;
if(!(wcp = fsp->wcp))
return;
allocated_write_caches--;
SMB_ASSERT(wcp->data_size == 0);
free(wcp->data);
free(wcp);
fsp->wcp = NULL;
}
/****************************************************************************
Setup the write cache structure.
****************************************************************************/
static BOOL setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
{
ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
write_cache *wcp;
if (allocated_write_caches >= MAX_WRITE_CACHES) return False;
if(alloc_size == 0 || fsp->wcp)
return False;
if((wcp = (write_cache *)malloc(sizeof(write_cache))) == NULL) {
DEBUG(0,("setup_write_cache: malloc fail.\n"));
return False;
}
wcp->file_size = file_size;
wcp->offset = 0;
wcp->alloc_size = alloc_size;
wcp->data_size = 0;
if((wcp->data = malloc(wcp->alloc_size)) == NULL) {
DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
(unsigned int)wcp->alloc_size ));
free(wcp);
return False;
}
fsp->wcp = wcp;
allocated_write_caches++;
return True;
}
/****************************************************************************
Cope with a size change.
****************************************************************************/
void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
{
if(fsp->wcp) {
flush_write_cache(fsp, SIZECHANGE_FLUSH);
fsp->wcp->file_size = file_size;
}
}
/*******************************************************************
Flush a write cache struct to disk.
********************************************************************/
ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
{
write_cache *wcp = fsp->wcp;
size_t data_size;
if(!wcp || !wcp->data_size)
return 0;
data_size = wcp->data_size;
wcp->data_size = 0;
num_write_caches--;
flush_reasons[(int)reason]++;
DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
fsp->fd_ptr->fd, (double)wcp->offset, (unsigned int)data_size));
if(data_size == wcp->alloc_size)
num_perfect_writes++;
return real_write_file(fsp, wcp->data, wcp->offset, data_size);
}
/*******************************************************************
sync a file
********************************************************************/
void sys_fsync_file(connection_struct *conn, files_struct *fsp)
{
if(lp_strict_sync(SNUM(conn)) && fsp->fd_ptr != NULL) {
flush_write_cache(fsp, SYNC_FLUSH);
conn->vfs_ops.fsync(fsp->fd_ptr->fd);
}
}