mfs: restore readonly mounting

. use dirty marking hooks to check and warn
	  when inodes/bufs are marked dirty on a readonly
	  mounted fs
	. add readonly mount checks to restore readonly
	  mounting

Signed-off-by: Ben Gras <ben@minix3.org>

servers/mfs/clean.h

@@ -2,7 +2,7 @@
 #ifndef _MFS_CLEAN_H
 #define _MFS_CLEAN_H 1
 
-#define MARKDIRTY(b) ((b)->b_dirt = BP_DIRTY)
+#define MARKDIRTY(b) do { if(superblock.s_dev == (b)->b_dev && superblock.s_rd_only) { printf("%s:%d: dirty block on rofs! ", __FILE__, __LINE__); util_stacktrace(); } else { (b)->b_dirt = BP_DIRTY; } } while(0)
 #define MARKCLEAN(b) ((b)->b_dirt = BP_CLEAN)
 
 #define ISDIRTY(b)	((b)->b_dirt == BP_DIRTY)

servers/mfs/inode.h

@@ -16,6 +16,8 @@
 
 #include <sys/queue.h>
 
+#include "super.h"
+
 EXTERN struct inode {
   u16_t i_mode;		/* file type, protection, etc. */
   u16_t i_nlinks;		/* how many links to this file */
@@ -63,7 +65,7 @@ EXTERN unsigned int inode_cache_miss;
 #define ISEEK              1	/* i_seek = ISEEK if last op was SEEK */
 
 #define IN_MARKCLEAN(i) i->i_dirt = IN_CLEAN
-#define IN_MARKDIRTY(i) i->i_dirt = IN_DIRTY
+#define IN_MARKDIRTY(i) do { if(i->i_sp->s_rd_only) { printf("%s:%d: dirty inode on rofs ", __FILE__, __LINE__); util_stacktrace(); } else { i->i_dirt = IN_DIRTY; } } while(0)
 
 #define IN_ISCLEAN(i) i->i_dirt == IN_CLEAN
 #define IN_ISDIRTY(i) i->i_dirt == IN_DIRTY

servers/mfs/link.c

@@ -148,8 +148,10 @@ PUBLIC int fs_unlink()
 	return(r);
   }
   
+  if(rip->i_sp->s_rd_only) {
+  	r = EROFS;
+  }  else if(fs_m_in.m_type == REQ_UNLINK) {
   /* Now test if the call is allowed, separately for unlink() and rmdir(). */
-  if(fs_m_in.m_type == REQ_UNLINK) {
 	  /* Only the su may unlink directories, but the su can unlink any
 	   * dir.*/
 	  if( (rip->i_mode & I_TYPE) == I_DIRECTORY) r = EPERM;
@@ -496,14 +498,18 @@ PUBLIC int fs_ftrunc(void)
   if( (rip = find_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
 	  return(EINVAL);
 
-  start = fs_m_in.REQ_TRC_START_LO;
-  end = fs_m_in.REQ_TRC_END_LO;
+  if(rip->i_sp->s_rd_only) {
+  	r = EROFS;
+  } else {
+    start = fs_m_in.REQ_TRC_START_LO;
+    end = fs_m_in.REQ_TRC_END_LO;
 
-  if (end == 0)
+    if (end == 0)
 	  r = truncate_inode(rip, start);
-  else 
+    else 
 	  r = freesp_inode(rip, start, end);
-  
+  }
+
   return(r);
 }
     

servers/mfs/path.c

@@ -494,6 +494,9 @@ int check_permissions;		 /* check permissions when flag is !IS_EMPTY */
   if ( (ldir_ptr->i_mode & I_TYPE) != I_DIRECTORY)  {
 	return(ENOTDIR);
    }
+
+  if((flag == DELETE || flag == ENTER) && ldir_ptr->i_sp->s_rd_only)
+	return EROFS;
   
   r = OK;
 

servers/mfs/protect.c

@@ -21,6 +21,11 @@ PUBLIC int fs_chmod()
   /* Temporarily open the file. */
   if( (rip = get_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
 	  return(EINVAL);
+ 
+  if(rip->i_sp->s_rd_only) {
+  	put_inode(rip);
+	return EROFS;
+  }
 
   /* Now make the change. Clear setgid bit if file is not in caller's grp */
   rip->i_mode = (rip->i_mode & ~ALL_MODES) | (mode & ALL_MODES);

servers/mfs/read.c

@@ -62,7 +62,11 @@ PUBLIC int fs_readwrite(void)
   
   rdwt_err = OK;		/* set to EIO if disk error occurs */
 
+  /* If this is file i/o, check we can write */
   if (rw_flag == WRITING && !block_spec) {
+  	  if(rip->i_sp->s_rd_only) 
+		  return EROFS;
+
 	  /* Check in advance to see if file will grow too big. */
 	  if (position > (off_t) (rip->i_sp->s_max_size - nrbytes))
 		  return(EFBIG);
@@ -73,6 +77,11 @@ PUBLIC int fs_readwrite(void)
 	   */
 	  if(position > f_size) clear_zone(rip, f_size, 0);
   }
+
+  /* If this is block i/o, check we can write */
+  if(block_spec && rw_flag == WRITING &&
+  	(dev_t) rip->i_zone[0] == superblock.s_dev && superblock.s_rd_only)
+		return EROFS;
 	      
   cum_io = 0;
   /* Split the transfer into chunks that don't span two blocks. */
@@ -114,7 +123,10 @@ PUBLIC int fs_readwrite(void)
   if (rdwt_err != OK) r = rdwt_err;	/* check for disk error */
   if (rdwt_err == END_OF_FILE) r = OK;
 
-  if (r == OK) {
+  /* even on a ROFS, writing to a device node on it is fine, 
+   * just don't update the inode stats for it. And dito for reading.
+   */
+  if (r == OK && !rip->i_sp->s_rd_only) {
 	  if (rw_flag == READING) rip->i_update |= ATIME;
 	  if (rw_flag == WRITING) rip->i_update |= CTIME | MTIME;
 	  IN_MARKDIRTY(rip);		/* inode is thus now dirty */
@@ -136,11 +148,14 @@ PUBLIC int fs_breadwrite(void)
   u64_t position;
   unsigned int off, cum_io, chunk, block_size;
   size_t nrbytes;
+  dev_t target_dev;
 
   /* Pseudo inode for rw_chunk */
   struct inode rip;
   
   r = OK;
+
+  target_dev = (dev_t) fs_m_in.REQ_DEV2;
   
   /* Get the values from the request message */ 
   rw_flag = (fs_m_in.m_type == REQ_BREAD ? READING : WRITING);
@@ -149,9 +164,13 @@ PUBLIC int fs_breadwrite(void)
   		    (unsigned long) fs_m_in.REQ_SEEK_POS_HI);
   nrbytes = (size_t) fs_m_in.REQ_NBYTES;
   
-  block_size = get_block_size( (dev_t) fs_m_in.REQ_DEV2);
+  block_size = get_block_size(target_dev);
 
-  rip.i_zone[0] = (zone_t) fs_m_in.REQ_DEV2;
+  /* Don't block-write to a RO-mounted filesystem. */
+  if(superblock.s_dev == target_dev && superblock.s_rd_only)
+  	return EROFS;
+
+  rip.i_zone[0] = (zone_t) target_dev;
   rip.i_mode = I_BLOCK_SPECIAL;
   rip.i_size = 0;
 
@@ -642,8 +661,10 @@ PUBLIC int fs_getdents(void)
   else {
 	  fs_m_out.RES_NBYTES = userbuf_off;
 	  fs_m_out.RES_SEEK_POS_LO = new_pos;
-	  rip->i_update |= ATIME;
-	  IN_MARKDIRTY(rip);
+	  if(!rip->i_sp->s_rd_only) {
+		  rip->i_update |= ATIME;
+		  IN_MARKDIRTY(rip);
+	  }
 	  r = OK;
   }