Merge pull request #2167 from ghaerr/fat

[kernel] Fix FAT filesystem adding blocks when seeking past EOF

elks/fs/msdos/fat.c

@@ -248,6 +248,7 @@ cluster_t FATPROC get_cluster(register struct inode *inode, cluster_t cluster)
 	cluster_t this, count;
 
 	if (!(this = inode->u.msdos_i.i_start)) return 0;
+	debug("get_cluster %ld = %ld\n", cluster, this);
 	if (!cluster) return this;
 	count = 0;
 	for (cache_lookup(inode,cluster,&count,&this); count < cluster; count++) {

elks/fs/msdos/file.c

@@ -101,6 +101,7 @@ static size_t msdos_file_write(register struct inode *inode,register struct file
 	int error;
 	char *start;
 	struct buffer_head *bh;
+	int dontuseisize;
 
 	debug_fat("file_write\n");
 	if (!inode) {
@@ -119,8 +120,11 @@ static size_t msdos_file_write(register struct inode *inode,register struct file
 	if (count <= 0) return 0;
 	error = 0;
 	for (start = buf; count; count -= size) {
-		while (!(sector = msdos_smap(inode,filp->f_pos >> SECTOR_BITS(inode))))
-			if ((error = msdos_add_cluster(inode)) < 0) break;
+		while (!(sector = msdos_smap(inode,filp->f_pos >> SECTOR_BITS(inode)))) {
+			/* don't use inode size in add_cluster if lseek past EOF */
+			dontuseisize = filp->f_pos > inode->i_size;
+			if ((error = msdos_add_cluster(inode, dontuseisize)) < 0) break;
+		}
 		if (error) break;
 		offset = (int)filp->f_pos & (SECTOR_SIZE(inode)-1);
 		size = MIN(SECTOR_SIZE(inode)-offset,count);

elks/fs/msdos/misc.c

@@ -60,7 +60,7 @@ void FATPROC unlock_creation(void)
 }
 
 
-int FATPROC msdos_add_cluster(register struct inode *inode)
+int FATPROC msdos_add_cluster(struct inode *inode, int dontuseisize)
 {
 	static struct wait_queue wait;
 	static int lock = 0;
@@ -84,7 +84,7 @@ int FATPROC msdos_add_cluster(register struct inode *inode)
 		this = ((count+prev) % limit)+2;
 		if (fat_access(inode->i_sb,this,-1L) == 0) break;
 	}
-	debug("free cluster: %d\r\n",this);
+	debug_fat("free cluster: %d\r\n",this);
 
 	prev = (count+prev+1) % limit;
 	sb->previous_cluster = prev;
@@ -102,7 +102,7 @@ int FATPROC msdos_add_cluster(register struct inode *inode)
 	wake_up(&wait);
 	debug("set to %x\r\n",fat_access(inode->i_sb,this,-1L));
 
-	if (!S_ISDIR(inode->i_mode)) {
+	if (!S_ISDIR(inode->i_mode) && !dontuseisize) {
 		last = inode->i_size?
 			get_cluster(inode,(inode->i_size-1) / SECTOR_SIZE(inode) / sb->cluster_size)
 			: 0;
@@ -117,15 +117,15 @@ int FATPROC msdos_add_cluster(register struct inode *inode)
 				}
 			}
 	}
-	debug("last = %d\r\n",last);
+	debug_fat("last = %d\r\n",last);
 
 	if (last)
 		fat_access(inode->i_sb,last,this);
 	else {
 		inode->u.msdos_i.i_start = this;
 		inode->i_dirt = 1;
 	}
-	if (last) debug("next set to %d\r\n",fat_access(inode->i_sb,last,-1L));
+	if (last) debug_fat("next set to %d\r\n",fat_access(inode->i_sb,last,-1L));
 
 	for (curr = 0; curr < sb->cluster_size; curr++) {
 		sector = sb->data_start + (this - 2) * sb->cluster_size + curr;
@@ -151,7 +151,7 @@ int FATPROC msdos_add_cluster(register struct inode *inode)
 			}
 		}
 		if (bh) {
-			debug_fat("add_cluster block write %lu\n", buffer_blocknr(bh));
+			debug("add_cluster block write %lu\n", buffer_blocknr(bh));
 			mark_buffer_dirty(bh);
 			brelse(bh);
 		}

elks/fs/msdos/namei.c

@@ -182,7 +182,7 @@ static int FATPROC msdos_create_entry(struct inode *dir,const char *name,int is_
 		/* if rootdir return no space*/
 		if (dir->i_ino == MSDOS_ROOT_INO) return -ENOSPC;
 		/* try adding space to directory*/
-		if ((res = msdos_add_cluster(dir)) < 0) return res;
+		if ((res = msdos_add_cluster(dir, 0)) < 0) return res;
 		/* if can't find empty entry return error*/
 		if ((res = msdos_scan(dir,NULL,&bh,&de,&ino)) < 0) return res;
 	}
@@ -259,7 +259,7 @@ int msdos_mkdir(struct inode *dir,const const char *name,size_t len,mode_t mode)
 	}
 
 	inode->u.msdos_i.i_busy = 1; /* prevent lookups */
-	if ((res = msdos_add_cluster(inode)) < 0) goto mkdir_error;
+	if ((res = msdos_add_cluster(inode, 0)) < 0) goto mkdir_error;
 	if ((res = msdos_create_entry(inode,MSDOS_DOT,1,&dot)) < 0)
 		goto mkdir_error;
 

elks/fs/open.c

@@ -240,7 +240,7 @@ int sys_open(const char *filename, int flags, mode_t mode)
     if ((flags + 1) & O_ACCMODE) flag++;
     if (flag & (O_TRUNC | O_CREAT)) flag |= FMODE_WRITE;
 
-    debug_cache("\nOPEN '%t' flags %02x ", filename, flags);
+    debug_file("\nOPEN '%t' flags %02x ", filename, flags);
     error = open_namei(filename, flag, mode, &inode, NULL);
     if (!error) {
         if ((error = open_fd(flags, inode)) < 0)

elks/fs/read_write.c

@@ -22,6 +22,7 @@ int sys_lseek(unsigned int fd, loff_t * p_offset, unsigned int origin)
     loff_t offset;
 
     offset = (loff_t) get_user_long(p_offset);
+    debug_file("lseek %d, %ld, %d\n", fd, offset, origin);
     if (fd >= NR_OPEN || !(file = current->files.fd[fd]) || !(file->f_inode))
 	return -EBADF;
     if (origin > 2) return -EINVAL;
@@ -97,6 +98,7 @@ int sys_write(unsigned int fd, char *buf, size_t count)
     register struct inode *inode;
     int written;
 
+    debug_file("write %d, buf, %u\n", fd, count);
     if (((written = fd_check(fd, buf, count, FMODE_WRITE, &file)) == 0) && count) {
 	written = -EINVAL;
 	fop = file->f_op;

elks/include/linuxmt/msdos_fs.h

@@ -121,7 +121,7 @@ struct buffer_head * FATPROC msdos_sread_nomap(struct super_block *s, sector_t s
 struct buffer_head * FATPROC msdos_sread(struct super_block *s, sector_t sector, void **start);
 void FATPROC lock_creation(void);
 void FATPROC unlock_creation(void);
-int  FATPROC msdos_add_cluster(struct inode *inode);
+int  FATPROC msdos_add_cluster(struct inode *inode, int dontuseisize);
 long FATPROC date_dos2unix(unsigned short time,unsigned short date);
 void FATPROC date_unix2dos(long unix_date,unsigned short *time, unsigned short *date);
 ino_t FATPROC msdos_get_entry(struct inode *dir,loff_t *pos,struct buffer_head **bh,