/*
* linux/fs/ext2/file.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* from
*
* linux/fs/minix/file.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* ext2 fs regular file handling primitives
*/
#include <asm/segment.h>
#include <asm/system.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/locks.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#define NBUF 32
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))
#include <linux/fs.h>
#include <linux/ext2_fs.h>
static int ext2_file_write (struct inode *, struct file *, const char *, int);
static void ext2_release_file (struct inode *, struct file *);
/*
* We have mostly NULL's here: the current defaults are ok for
* the ext2 filesystem.
*/
static struct file_operations ext2_file_operations = {
NULL, /* lseek - default */
generic_file_read, /* read */
ext2_file_write, /* write */
NULL, /* readdir - bad */
NULL, /* select - default */
ext2_ioctl, /* ioctl */
generic_file_mmap, /* mmap */
NULL, /* no special open is needed */
ext2_release_file, /* release */
ext2_sync_file, /* fsync */
NULL, /* fasync */
NULL, /* check_media_change */
NULL /* revalidate */
};
struct inode_operations ext2_file_inode_operations = {
&ext2_file_operations,/* default file operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
NULL, /* readlink */
NULL, /* follow_link */
generic_readpage, /* readpage */
NULL, /* writepage */
ext2_bmap, /* bmap */
ext2_truncate, /* truncate */
ext2_permission, /* permission */
NULL /* smap */
};
static int ext2_file_write (struct inode * inode, struct file * filp,
const char * buf, int count)
/*KOMENTOWAL: ADAM KIEZUN*/
/*To jest ta czesc funkcji write, która jest zalezna od systemu plików - ta jest dla EXT2*/
{
const loff_t two_gb = 2147483647;
loff_t pos;
off_t pos2;
long block;
int offset;
int written, c;
struct buffer_head * bh, *bufferlist[NBUF]; /*tablica buforów*/
struct super_block * sb;
int err;
int i,buffercount,write_error;
write_error = buffercount = 0;
if (!inode) { /*brak i-wezla*/
printk("ext2_file_write: inode = NULL\n");
return -EINVAL;
}
sb = inode->i_sb;
if (sb->s_flags & MS_RDONLY)
return -ENOSPC;
if (!S_ISREG(inode->i_mode)) { /*plik ma byc regularny*/
ext2_warning (sb, "ext2_file_write", "mode = %07o",
inode->i_mode);
return -EINVAL;
}
/*ustawmy biezaca pozycje*/
if (filp->f_flags & O_APPEND) /*jesli to plik do dopisywania, to ustaw znacznik na koncu*/
pos = inode->i_size;
else
pos = filp->f_pos; /*wpp znacznik zostaje gdzie byl*/
pos2 = (off_t) pos; /*przesuniecie wewnatrz bloku*/
if (filp->f_flags & O_SYNC)
inode->u.ext2_i.i_osync++;
/*obliczamy numer bloku, do którego bedziemy pisac*/
block = pos2 >> EXT2_BLOCK_SIZE_BITS(sb)
/*i miejsce w tym bloku*/
offset = pos2 & (sb->s_blocksize - 1);
c = sb->s_blocksize - offset; /*tyle bajtów zapisujemy*/
written = 0;
while (count > 0) { /*dopóki cos jest do zapisania*/
if (pos > two_gb) { /*plik nie moze byc dluzszy niz 2gB*/
if (!written)
written = -EFBIG;
break;
}
bh = ext2_getblk (inode, block, 1, &err); /*pobieramy bufor*/
if (!bh) { /*nie dostalismy bufora*/
if (!written)
written = err;
break;
}
count -= c; /*tyle zostalo do zapisania*/
if (count < 0)
c += count;
/*nie bedziemy zapisywac bloku w calosci, wiec trzeba go najpierw wczytac*/
if (c != sb->s_blocksize && !buffer_uptodate(bh)) {
ll_rw_block (READ, 1, &bh);
wait_on_buffer (bh);
if (!buffer_uptodate(bh)) { /*zwolnic go - i tak byl nieaktualny*/
brelse (bh);
if (!written)
written = -EIO;
break;
}
}
memcpy_fromfs (bh->b_data + offset, buf, c); /*kopujamy dane z pamieci
do otrzymanego bufora*/
/*uaktualnia kopie strony*/
update_vm_cache(inode, pos, bh->b_data + offset, c);
/*przesuwamy sie w pliku i w buforze wejscia*/
pos2 += c;
pos += c;
written += c;
buf += c;
mark_buffer_uptodate(bh, 1); /*buffor jest aktualny*/
mark_buffer_dirty(bh, 0); /*ale nie jest brudny*/
if (filp->f_flags & O_SYNC) /*jesli plik jest synchroniczny to wpisujemy bufor
do tablicy buforów - pisanie z opóznieniem*/
bufferlist[buffercount++] = bh;
else
brelse(bh);/*wpp zwalniamy natychmast bufor*/
if (buffercount == NBUF){ /*jesli tablica buforów jest pelna, to ja zapisujemy na
*/
ll_rw_block(WRITE, buffercount, bufferlist);
for(i=0; i<buffercount; i++){
wait_on_buffer(bufferlist[i]);/*bierzemy mucha*/
if (!buffer_uptodate(bufferlist[i]))
write_error=1;
brelse(bufferlist[i]);/*zwalniamy bufor*/
}
buffercount=0;/*i zapelniamy te tablice jeszcze raz od nowa*/
}
if(write_error)
break;
block++;
offset = 0; /*od poczatku bufora*/
c = sb->s_blocksize;
}/*koniec petli while*/
if ( buffercount ){ /*cos zostalo w tablicy buforów*/
ll_rw_block(WRITE, buffercount, bufferlist); /*zapisac to*/
for(i=0; i<buffercount; i++){
wait_on_buffer(bufferlist[i]); /*czakamy na bufor*/
if (!buffer_uptodate(bufferlist[i]))
write_error=1;
brelse(bufferlist[i]); /*zwolnic go*/
}
}
if (pos > inode->i_size)
inode->i_size = pos; /*jesli teraz pozycja jest wyzsza niz
poprzednia wielkosc pliku; to znaczy,
ze plik sie wydluzyl*/
if (filp->f_flags & O_SYNC)
inode->u.ext2_i.i_osync--;
inode->i_ctime = inode->i_mtime = CURRENT_TIME; /*czas modyfikacji*/
filp->f_pos = pos; /*nowa pozycja w pliku*/
inode->i_dirt = 1; /*i-wezel jest rózny od tego na dysku*/
return written; /*oto ile zapisano*/
}
/*
* Called when a inode is released. Note that this is different
* from ext2_open: open gets called at every open, but release
* gets called only when /all/ the files are closed.
*/
static void ext2_release_file (struct inode * inode, struct file * filp)
{
if (filp->f_mode & 2)
ext2_discard_prealloc (inode);
}