xref: /minix3/minix/fs/mfs/write.c (revision 4472b590c74fed661146a925d8dff2ed1b04256e)
1433d6423SLionel Sambuc /* This file is the counterpart of "read.c".  It contains the code for writing
2433d6423SLionel Sambuc  * insofar as this is not contained in fs_readwrite().
3433d6423SLionel Sambuc  *
4433d6423SLionel Sambuc  * The entry points into this file are
5433d6423SLionel Sambuc  *   write_map:    write a new zone into an inode
6433d6423SLionel Sambuc  *   clear_zone:   erase a zone in the middle of a file
7433d6423SLionel Sambuc  *   new_block:    acquire a new block
8433d6423SLionel Sambuc  *   zero_block:   overwrite a block with zeroes
9433d6423SLionel Sambuc  *
10433d6423SLionel Sambuc  */
11433d6423SLionel Sambuc 
12433d6423SLionel Sambuc #include "fs.h"
13433d6423SLionel Sambuc #include <string.h>
14433d6423SLionel Sambuc #include <assert.h>
15433d6423SLionel Sambuc #include <sys/param.h>
16433d6423SLionel Sambuc #include "buf.h"
17433d6423SLionel Sambuc #include "inode.h"
18433d6423SLionel Sambuc #include "super.h"
19433d6423SLionel Sambuc 
20433d6423SLionel Sambuc 
21433d6423SLionel Sambuc static void wr_indir(struct buf *bp, int index, zone_t zone);
22433d6423SLionel Sambuc static int empty_indir(struct buf *, struct super_block *);
23433d6423SLionel Sambuc 
24433d6423SLionel Sambuc 
25433d6423SLionel Sambuc /*===========================================================================*
26433d6423SLionel Sambuc  *				write_map				     *
27433d6423SLionel Sambuc  *===========================================================================*/
write_map(rip,position,new_zone,op)28433d6423SLionel Sambuc int write_map(rip, position, new_zone, op)
29433d6423SLionel Sambuc struct inode *rip;		/* pointer to inode to be changed */
30433d6423SLionel Sambuc off_t position;			/* file address to be mapped */
31433d6423SLionel Sambuc zone_t new_zone;		/* zone # to be inserted */
32433d6423SLionel Sambuc int op;				/* special actions */
33433d6423SLionel Sambuc {
34433d6423SLionel Sambuc /* Write a new zone into an inode.
35433d6423SLionel Sambuc  *
36433d6423SLionel Sambuc  * If op includes WMAP_FREE, free the data zone corresponding to that position
37433d6423SLionel Sambuc  * in the inode ('new_zone' is ignored then). Also free the indirect block
38433d6423SLionel Sambuc  * if that was the last entry in the indirect block.
39433d6423SLionel Sambuc  * Also free the double indirect block if that was the last entry in the
40433d6423SLionel Sambuc  * double indirect block.
41433d6423SLionel Sambuc  */
42433d6423SLionel Sambuc   int scale, ind_ex = 0, new_ind, new_dbl,
43433d6423SLionel Sambuc         zones, nr_indirects, single, zindex, ex;
44433d6423SLionel Sambuc   zone_t z, z1, z2 = NO_ZONE, old_zone;
45433d6423SLionel Sambuc   register block_t b;
46433d6423SLionel Sambuc   long excess, zone;
47433d6423SLionel Sambuc   struct buf *bp_dindir = NULL, *bp = NULL;
48433d6423SLionel Sambuc 
49433d6423SLionel Sambuc   IN_MARKDIRTY(rip);
50433d6423SLionel Sambuc   scale = rip->i_sp->s_log_zone_size;		/* for zone-block conversion */
51433d6423SLionel Sambuc   	/* relative zone # to insert */
52433d6423SLionel Sambuc   zone = (position/rip->i_sp->s_block_size) >> scale;
53433d6423SLionel Sambuc   zones = rip->i_ndzones;	/* # direct zones in the inode */
54433d6423SLionel Sambuc   nr_indirects = rip->i_nindirs;/* # indirect zones per indirect block */
55433d6423SLionel Sambuc 
56433d6423SLionel Sambuc   /* Is 'position' to be found in the inode itself? */
57433d6423SLionel Sambuc   if (zone < zones) {
58433d6423SLionel Sambuc 	zindex = (int) zone;	/* we need an integer here */
59433d6423SLionel Sambuc 	if(rip->i_zone[zindex] != NO_ZONE && (op & WMAP_FREE)) {
60433d6423SLionel Sambuc 		free_zone(rip->i_dev, rip->i_zone[zindex]);
61433d6423SLionel Sambuc 		rip->i_zone[zindex] = NO_ZONE;
62433d6423SLionel Sambuc 	} else {
63433d6423SLionel Sambuc 		rip->i_zone[zindex] = new_zone;
64433d6423SLionel Sambuc 	}
65433d6423SLionel Sambuc 	return(OK);
66433d6423SLionel Sambuc   }
67433d6423SLionel Sambuc 
68433d6423SLionel Sambuc   /* It is not in the inode, so it must be single or double indirect. */
69433d6423SLionel Sambuc   excess = zone - zones;	/* first Vx_NR_DZONES don't count */
70433d6423SLionel Sambuc   new_ind = FALSE;
71433d6423SLionel Sambuc   new_dbl = FALSE;
72433d6423SLionel Sambuc 
73433d6423SLionel Sambuc   if (excess < nr_indirects) {
74433d6423SLionel Sambuc 	/* 'position' can be located via the single indirect block. */
75433d6423SLionel Sambuc 	z1 = rip->i_zone[zones];	/* single indirect zone */
76433d6423SLionel Sambuc 	single = TRUE;
77433d6423SLionel Sambuc   } else {
78433d6423SLionel Sambuc 	/* 'position' can be located via the double indirect block. */
79433d6423SLionel Sambuc 	if ( (z2 = z = rip->i_zone[zones+1]) == NO_ZONE &&
80433d6423SLionel Sambuc 	    !(op & WMAP_FREE)) {
81433d6423SLionel Sambuc 		/* Create the double indirect block. */
82433d6423SLionel Sambuc 		if ( (z = alloc_zone(rip->i_dev, rip->i_zone[0])) == NO_ZONE)
83433d6423SLionel Sambuc 			return(err_code);
84433d6423SLionel Sambuc 		rip->i_zone[zones+1] = z;
85433d6423SLionel Sambuc 		new_dbl = TRUE;	/* set flag for later */
86433d6423SLionel Sambuc 	}
87433d6423SLionel Sambuc 
88433d6423SLionel Sambuc 	/* 'z' is zone number for double indirect block, either old
89433d6423SLionel Sambuc 	 * or newly created.
90433d6423SLionel Sambuc 	 * If there wasn't one and WMAP_FREE is set, 'z' is NO_ZONE.
91433d6423SLionel Sambuc 	 */
92433d6423SLionel Sambuc 	excess -= nr_indirects;	/* single indirect doesn't count */
93433d6423SLionel Sambuc 	ind_ex = (int) (excess / nr_indirects);
94433d6423SLionel Sambuc 	excess = excess % nr_indirects;
95433d6423SLionel Sambuc 	if (ind_ex >= nr_indirects) return(EFBIG);
96433d6423SLionel Sambuc 
97433d6423SLionel Sambuc 	if(z == NO_ZONE && (op & WMAP_FREE)) {
98433d6423SLionel Sambuc 		/* WMAP_FREE and no double indirect block - then no
99433d6423SLionel Sambuc 		 * single indirect block either.
100433d6423SLionel Sambuc 		 */
101433d6423SLionel Sambuc 		z1 = NO_ZONE;
102433d6423SLionel Sambuc 	} else {
103433d6423SLionel Sambuc 		b = (block_t) z << scale;
104433d6423SLionel Sambuc 		bp_dindir = get_block(rip->i_dev, b,
105433d6423SLionel Sambuc 			(new_dbl?NO_READ:NORMAL));
106433d6423SLionel Sambuc 		if (new_dbl) zero_block(bp_dindir);
107433d6423SLionel Sambuc 		z1 = rd_indir(bp_dindir, ind_ex);
108433d6423SLionel Sambuc 	}
109433d6423SLionel Sambuc 	single = FALSE;
110433d6423SLionel Sambuc   }
111433d6423SLionel Sambuc 
112433d6423SLionel Sambuc   /* z1 is now single indirect zone, or NO_ZONE; 'excess' is index.
113433d6423SLionel Sambuc    * We have to create the indirect zone if it's NO_ZONE. Unless
114433d6423SLionel Sambuc    * we're freeing (WMAP_FREE).
115433d6423SLionel Sambuc    */
116433d6423SLionel Sambuc   if (z1 == NO_ZONE && !(op & WMAP_FREE)) {
117433d6423SLionel Sambuc 	z1 = alloc_zone(rip->i_dev, rip->i_zone[0]);
118433d6423SLionel Sambuc 	if (single)
119433d6423SLionel Sambuc 		rip->i_zone[zones] = z1; /* update inode w. single indirect */
120433d6423SLionel Sambuc 	else
121433d6423SLionel Sambuc 		wr_indir(bp_dindir, ind_ex, z1);	/* update dbl indir */
122433d6423SLionel Sambuc 
123433d6423SLionel Sambuc 	new_ind = TRUE;
124433d6423SLionel Sambuc 	/* If double ind, it is dirty. */
125433d6423SLionel Sambuc 	if (bp_dindir != NULL) MARKDIRTY(bp_dindir);
126433d6423SLionel Sambuc 	if (z1 == NO_ZONE) {
127433d6423SLionel Sambuc 		/* Release dbl indirect blk. */
1280314acfbSDavid van Moolenbroek 		put_block(bp_dindir);
129433d6423SLionel Sambuc 		return(err_code);	/* couldn't create single ind */
130433d6423SLionel Sambuc 	}
131433d6423SLionel Sambuc   }
132433d6423SLionel Sambuc 
133433d6423SLionel Sambuc   /* z1 is indirect block's zone number (unless it's NO_ZONE when we're
134433d6423SLionel Sambuc    * freeing).
135433d6423SLionel Sambuc    */
136433d6423SLionel Sambuc   if(z1 != NO_ZONE) {
137433d6423SLionel Sambuc   	ex = (int) excess;			/* we need an int here */
138433d6423SLionel Sambuc 	b = (block_t) z1 << scale;
139433d6423SLionel Sambuc 	bp = get_block(rip->i_dev, b, (new_ind ? NO_READ : NORMAL) );
140433d6423SLionel Sambuc 	if (new_ind) zero_block(bp);
141433d6423SLionel Sambuc 	if(op & WMAP_FREE) {
142433d6423SLionel Sambuc 		if((old_zone = rd_indir(bp, ex)) != NO_ZONE) {
143433d6423SLionel Sambuc 			free_zone(rip->i_dev, old_zone);
144433d6423SLionel Sambuc 			wr_indir(bp, ex, NO_ZONE);
145433d6423SLionel Sambuc 		}
146433d6423SLionel Sambuc 
147433d6423SLionel Sambuc 		/* Last reference in the indirect block gone? Then
148433d6423SLionel Sambuc 		 * free the indirect block.
149433d6423SLionel Sambuc 		 */
150433d6423SLionel Sambuc 		if(empty_indir(bp, rip->i_sp)) {
151433d6423SLionel Sambuc 			free_zone(rip->i_dev, z1);
152433d6423SLionel Sambuc 			z1 = NO_ZONE;
153433d6423SLionel Sambuc 			/* Update the reference to the indirect block to
154433d6423SLionel Sambuc 			 * NO_ZONE - in the double indirect block if there
155433d6423SLionel Sambuc 			 * is one, otherwise in the inode directly.
156433d6423SLionel Sambuc 			 */
157433d6423SLionel Sambuc 			if(single) {
158433d6423SLionel Sambuc 				rip->i_zone[zones] = z1;
159433d6423SLionel Sambuc 			} else {
160433d6423SLionel Sambuc 				wr_indir(bp_dindir, ind_ex, z1);
161433d6423SLionel Sambuc 				MARKDIRTY(bp_dindir);
162433d6423SLionel Sambuc 			}
163433d6423SLionel Sambuc 		}
164433d6423SLionel Sambuc 	} else {
165433d6423SLionel Sambuc 		wr_indir(bp, ex, new_zone);
166433d6423SLionel Sambuc 	}
167433d6423SLionel Sambuc 	/* z1 equals NO_ZONE only when we are freeing up the indirect block. */
168e94f856bSDavid van Moolenbroek 	if(z1 != NO_ZONE) MARKDIRTY(bp);
1690314acfbSDavid van Moolenbroek 	put_block(bp);
170433d6423SLionel Sambuc   }
171433d6423SLionel Sambuc 
172433d6423SLionel Sambuc   /* If the single indirect block isn't there (or was just freed),
173433d6423SLionel Sambuc    * see if we have to keep the double indirect block, if any.
174433d6423SLionel Sambuc    * If we don't have to keep it, don't bother writing it out.
175433d6423SLionel Sambuc    */
176433d6423SLionel Sambuc   if(z1 == NO_ZONE && !single && z2 != NO_ZONE &&
177433d6423SLionel Sambuc      empty_indir(bp_dindir, rip->i_sp)) {
178433d6423SLionel Sambuc 	free_zone(rip->i_dev, z2);
179433d6423SLionel Sambuc 	rip->i_zone[zones+1] = NO_ZONE;
180433d6423SLionel Sambuc   }
181433d6423SLionel Sambuc 
1820314acfbSDavid van Moolenbroek   put_block(bp_dindir);			/* release double indirect blk */
183433d6423SLionel Sambuc 
184433d6423SLionel Sambuc   return(OK);
185433d6423SLionel Sambuc }
186433d6423SLionel Sambuc 
187433d6423SLionel Sambuc 
188433d6423SLionel Sambuc /*===========================================================================*
189433d6423SLionel Sambuc  *				wr_indir				     *
190433d6423SLionel Sambuc  *===========================================================================*/
wr_indir(bp,index,zone)191433d6423SLionel Sambuc static void wr_indir(bp, index, zone)
192433d6423SLionel Sambuc struct buf *bp;			/* pointer to indirect block */
193433d6423SLionel Sambuc int index;			/* index into *bp */
194433d6423SLionel Sambuc zone_t zone;			/* zone to write */
195433d6423SLionel Sambuc {
196433d6423SLionel Sambuc /* Given a pointer to an indirect block, write one entry. */
197433d6423SLionel Sambuc 
198433d6423SLionel Sambuc   struct super_block *sp;
199433d6423SLionel Sambuc 
200433d6423SLionel Sambuc   if(bp == NULL)
201433d6423SLionel Sambuc 	panic("wr_indir() on NULL");
202433d6423SLionel Sambuc 
203*4472b590SDavid van Moolenbroek   sp = &superblock;
204433d6423SLionel Sambuc 
205433d6423SLionel Sambuc   /* write a zone into an indirect block */
206433d6423SLionel Sambuc   assert(sp->s_version == V3);
207433d6423SLionel Sambuc   b_v2_ind(bp)[index] = (zone_t)  conv4(sp->s_native, (long) zone);
208433d6423SLionel Sambuc }
209433d6423SLionel Sambuc 
210433d6423SLionel Sambuc 
211433d6423SLionel Sambuc /*===========================================================================*
212433d6423SLionel Sambuc  *				empty_indir				     *
213433d6423SLionel Sambuc  *===========================================================================*/
empty_indir(bp,sb)214433d6423SLionel Sambuc static int empty_indir(bp, sb)
215433d6423SLionel Sambuc struct buf *bp;			/* pointer to indirect block */
216433d6423SLionel Sambuc struct super_block *sb;		/* superblock of device block resides on */
217433d6423SLionel Sambuc {
218433d6423SLionel Sambuc /* Return nonzero if the indirect block pointed to by bp contains
219433d6423SLionel Sambuc  * only NO_ZONE entries.
220433d6423SLionel Sambuc  */
221433d6423SLionel Sambuc   unsigned int i;
222433d6423SLionel Sambuc   for(i = 0; i < V2_INDIRECTS(sb->s_block_size); i++)
223433d6423SLionel Sambuc 	if( b_v2_ind(bp)[i] != NO_ZONE)
224433d6423SLionel Sambuc 		return(0);
225433d6423SLionel Sambuc 
226433d6423SLionel Sambuc   return(1);
227433d6423SLionel Sambuc }
228433d6423SLionel Sambuc 
229433d6423SLionel Sambuc 
230433d6423SLionel Sambuc /*===========================================================================*
231433d6423SLionel Sambuc  *				clear_zone				     *
232433d6423SLionel Sambuc  *===========================================================================*/
clear_zone(rip,pos,flag)233433d6423SLionel Sambuc void clear_zone(rip, pos, flag)
234433d6423SLionel Sambuc register struct inode *rip;	/* inode to clear */
235ccaeedb2SDavid van Moolenbroek off_t __unused pos;		/* points to block to clear */
236ccaeedb2SDavid van Moolenbroek int __unused flag;		/* 1 if called by new_block, 0 otherwise */
237433d6423SLionel Sambuc {
238433d6423SLionel Sambuc /* Zero a zone, possibly starting in the middle.  The parameter 'pos' gives
239433d6423SLionel Sambuc  * a byte in the first block to be zeroed.  Clearzone() is called from
240433d6423SLionel Sambuc  * fs_readwrite(), truncate_inode(), and new_block().
241433d6423SLionel Sambuc  */
242433d6423SLionel Sambuc   int scale;
243433d6423SLionel Sambuc 
244433d6423SLionel Sambuc   /* If the block size and zone size are the same, clear_zone() not needed. */
245433d6423SLionel Sambuc   scale = rip->i_sp->s_log_zone_size;
246433d6423SLionel Sambuc   assert(scale == 0);
247433d6423SLionel Sambuc   return;
248433d6423SLionel Sambuc }
249433d6423SLionel Sambuc 
250433d6423SLionel Sambuc 
251433d6423SLionel Sambuc /*===========================================================================*
252433d6423SLionel Sambuc  *				new_block				     *
253433d6423SLionel Sambuc  *===========================================================================*/
new_block(rip,position)254433d6423SLionel Sambuc struct buf *new_block(rip, position)
255433d6423SLionel Sambuc register struct inode *rip;	/* pointer to inode */
256433d6423SLionel Sambuc off_t position;			/* file pointer */
257433d6423SLionel Sambuc {
258433d6423SLionel Sambuc /* Acquire a new block and return a pointer to it.  Doing so may require
259433d6423SLionel Sambuc  * allocating a complete zone, and then returning the initial block.
260433d6423SLionel Sambuc  * On the other hand, the current zone may still have some unused blocks.
261433d6423SLionel Sambuc  */
2626c46a77dSDavid van Moolenbroek   struct buf *bp;
263433d6423SLionel Sambuc   block_t b, base_block;
264433d6423SLionel Sambuc   zone_t z;
265433d6423SLionel Sambuc   zone_t zone_size;
266433d6423SLionel Sambuc   int scale, r;
267433d6423SLionel Sambuc 
268433d6423SLionel Sambuc   /* Is another block available in the current zone? */
269433d6423SLionel Sambuc   if ( (b = read_map(rip, position, 0)) == NO_BLOCK) {
270433d6423SLionel Sambuc 	if (rip->i_zsearch == NO_ZONE) {
271433d6423SLionel Sambuc 		/* First search for this file. Start looking from
272433d6423SLionel Sambuc 		 * the file's first data zone to prevent fragmentation
273433d6423SLionel Sambuc 		 */
274433d6423SLionel Sambuc 		if ( (z = rip->i_zone[0]) == NO_ZONE) {
275433d6423SLionel Sambuc 		 	/* No first zone for file either, let alloc_zone
276433d6423SLionel Sambuc 		 	 * decide. */
277433d6423SLionel Sambuc 			z = (zone_t) rip->i_sp->s_firstdatazone;
278433d6423SLionel Sambuc 		}
279433d6423SLionel Sambuc 	} else {
280433d6423SLionel Sambuc 		/* searched before, start from last find */
281433d6423SLionel Sambuc 		z = rip->i_zsearch;
282433d6423SLionel Sambuc 	}
283433d6423SLionel Sambuc 	if ( (z = alloc_zone(rip->i_dev, z)) == NO_ZONE) return(NULL);
284433d6423SLionel Sambuc 	rip->i_zsearch = z;	/* store for next lookup */
285433d6423SLionel Sambuc 	if ( (r = write_map(rip, position, z, 0)) != OK) {
286433d6423SLionel Sambuc 		free_zone(rip->i_dev, z);
287433d6423SLionel Sambuc 		err_code = r;
288433d6423SLionel Sambuc 		return(NULL);
289433d6423SLionel Sambuc 	}
290433d6423SLionel Sambuc 
291433d6423SLionel Sambuc 	/* If we are not writing at EOF, clear the zone, just to be safe. */
292433d6423SLionel Sambuc 	if ( position != rip->i_size) clear_zone(rip, position, 1);
293433d6423SLionel Sambuc 	scale = rip->i_sp->s_log_zone_size;
294433d6423SLionel Sambuc 	base_block = (block_t) z << scale;
295433d6423SLionel Sambuc 	zone_size = (zone_t) rip->i_sp->s_block_size << scale;
296433d6423SLionel Sambuc 	b = base_block + (block_t)((position % zone_size)/rip->i_sp->s_block_size);
297433d6423SLionel Sambuc   }
298433d6423SLionel Sambuc 
2996c46a77dSDavid van Moolenbroek   r = lmfs_get_block_ino(&bp, rip->i_dev, b, NO_READ, rip->i_num,
300433d6423SLionel Sambuc   	rounddown(position, rip->i_sp->s_block_size));
3016c46a77dSDavid van Moolenbroek   if (r != OK)
3026c46a77dSDavid van Moolenbroek 	panic("MFS: error getting block (%llu,%u): %d", rip->i_dev, b, r);
303433d6423SLionel Sambuc   zero_block(bp);
304433d6423SLionel Sambuc   return(bp);
305433d6423SLionel Sambuc }
306433d6423SLionel Sambuc 
307433d6423SLionel Sambuc 
308433d6423SLionel Sambuc /*===========================================================================*
309433d6423SLionel Sambuc  *				zero_block				     *
310433d6423SLionel Sambuc  *===========================================================================*/
zero_block(bp)311433d6423SLionel Sambuc void zero_block(bp)
312433d6423SLionel Sambuc register struct buf *bp;	/* pointer to buffer to zero */
313433d6423SLionel Sambuc {
314433d6423SLionel Sambuc /* Zero a block. */
315433d6423SLionel Sambuc   ASSERT(bp->data);
3160314acfbSDavid van Moolenbroek   memset(b_data(bp), 0, lmfs_fs_block_size());
317433d6423SLionel Sambuc   MARKDIRTY(bp);
318433d6423SLionel Sambuc }
319433d6423SLionel Sambuc 
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