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Linux/fs/gfs2/meta_io.c

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  1 /*
  2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
  3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
  4  *
  5  * This copyrighted material is made available to anyone wishing to use,
  6  * modify, copy, or redistribute it subject to the terms and conditions
  7  * of the GNU General Public License version 2.
  8  */
  9 
 10 #include <linux/sched.h>
 11 #include <linux/slab.h>
 12 #include <linux/spinlock.h>
 13 #include <linux/completion.h>
 14 #include <linux/buffer_head.h>
 15 #include <linux/mm.h>
 16 #include <linux/pagemap.h>
 17 #include <linux/writeback.h>
 18 #include <linux/swap.h>
 19 #include <linux/delay.h>
 20 #include <linux/bio.h>
 21 #include <linux/gfs2_ondisk.h>
 22 
 23 #include "gfs2.h"
 24 #include "incore.h"
 25 #include "glock.h"
 26 #include "glops.h"
 27 #include "inode.h"
 28 #include "log.h"
 29 #include "lops.h"
 30 #include "meta_io.h"
 31 #include "rgrp.h"
 32 #include "trans.h"
 33 #include "util.h"
 34 #include "trace_gfs2.h"
 35 
 36 static int gfs2_aspace_writepage(struct page *page, struct writeback_control *wbc)
 37 {
 38         struct buffer_head *bh, *head;
 39         int nr_underway = 0;
 40         int write_flags = REQ_META | REQ_PRIO | wbc_to_write_flags(wbc);
 41 
 42         BUG_ON(!PageLocked(page));
 43         BUG_ON(!page_has_buffers(page));
 44 
 45         head = page_buffers(page);
 46         bh = head;
 47 
 48         do {
 49                 if (!buffer_mapped(bh))
 50                         continue;
 51                 /*
 52                  * If it's a fully non-blocking write attempt and we cannot
 53                  * lock the buffer then redirty the page.  Note that this can
 54                  * potentially cause a busy-wait loop from flusher thread and kswapd
 55                  * activity, but those code paths have their own higher-level
 56                  * throttling.
 57                  */
 58                 if (wbc->sync_mode != WB_SYNC_NONE) {
 59                         lock_buffer(bh);
 60                 } else if (!trylock_buffer(bh)) {
 61                         redirty_page_for_writepage(wbc, page);
 62                         continue;
 63                 }
 64                 if (test_clear_buffer_dirty(bh)) {
 65                         mark_buffer_async_write(bh);
 66                 } else {
 67                         unlock_buffer(bh);
 68                 }
 69         } while ((bh = bh->b_this_page) != head);
 70 
 71         /*
 72          * The page and its buffers are protected by PageWriteback(), so we can
 73          * drop the bh refcounts early.
 74          */
 75         BUG_ON(PageWriteback(page));
 76         set_page_writeback(page);
 77 
 78         do {
 79                 struct buffer_head *next = bh->b_this_page;
 80                 if (buffer_async_write(bh)) {
 81                         submit_bh(REQ_OP_WRITE, write_flags, bh);
 82                         nr_underway++;
 83                 }
 84                 bh = next;
 85         } while (bh != head);
 86         unlock_page(page);
 87 
 88         if (nr_underway == 0)
 89                 end_page_writeback(page);
 90 
 91         return 0;
 92 }
 93 
 94 const struct address_space_operations gfs2_meta_aops = {
 95         .writepage = gfs2_aspace_writepage,
 96         .releasepage = gfs2_releasepage,
 97 };
 98 
 99 const struct address_space_operations gfs2_rgrp_aops = {
100         .writepage = gfs2_aspace_writepage,
101         .releasepage = gfs2_releasepage,
102 };
103 
104 /**
105  * gfs2_getbuf - Get a buffer with a given address space
106  * @gl: the glock
107  * @blkno: the block number (filesystem scope)
108  * @create: 1 if the buffer should be created
109  *
110  * Returns: the buffer
111  */
112 
113 struct buffer_head *gfs2_getbuf(struct gfs2_glock *gl, u64 blkno, int create)
114 {
115         struct address_space *mapping = gfs2_glock2aspace(gl);
116         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
117         struct page *page;
118         struct buffer_head *bh;
119         unsigned int shift;
120         unsigned long index;
121         unsigned int bufnum;
122 
123         if (mapping == NULL)
124                 mapping = &sdp->sd_aspace;
125 
126         shift = PAGE_SHIFT - sdp->sd_sb.sb_bsize_shift;
127         index = blkno >> shift;             /* convert block to page */
128         bufnum = blkno - (index << shift);  /* block buf index within page */
129 
130         if (create) {
131                 for (;;) {
132                         page = grab_cache_page(mapping, index);
133                         if (page)
134                                 break;
135                         yield();
136                 }
137         } else {
138                 page = find_get_page_flags(mapping, index,
139                                                 FGP_LOCK|FGP_ACCESSED);
140                 if (!page)
141                         return NULL;
142         }
143 
144         if (!page_has_buffers(page))
145                 create_empty_buffers(page, sdp->sd_sb.sb_bsize, 0);
146 
147         /* Locate header for our buffer within our page */
148         for (bh = page_buffers(page); bufnum--; bh = bh->b_this_page)
149                 /* Do nothing */;
150         get_bh(bh);
151 
152         if (!buffer_mapped(bh))
153                 map_bh(bh, sdp->sd_vfs, blkno);
154 
155         unlock_page(page);
156         put_page(page);
157 
158         return bh;
159 }
160 
161 static void meta_prep_new(struct buffer_head *bh)
162 {
163         struct gfs2_meta_header *mh = (struct gfs2_meta_header *)bh->b_data;
164 
165         lock_buffer(bh);
166         clear_buffer_dirty(bh);
167         set_buffer_uptodate(bh);
168         unlock_buffer(bh);
169 
170         mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
171 }
172 
173 /**
174  * gfs2_meta_new - Get a block
175  * @gl: The glock associated with this block
176  * @blkno: The block number
177  *
178  * Returns: The buffer
179  */
180 
181 struct buffer_head *gfs2_meta_new(struct gfs2_glock *gl, u64 blkno)
182 {
183         struct buffer_head *bh;
184         bh = gfs2_getbuf(gl, blkno, CREATE);
185         meta_prep_new(bh);
186         return bh;
187 }
188 
189 static void gfs2_meta_read_endio(struct bio *bio)
190 {
191         struct bio_vec *bvec;
192         int i;
193 
194         bio_for_each_segment_all(bvec, bio, i) {
195                 struct page *page = bvec->bv_page;
196                 struct buffer_head *bh = page_buffers(page);
197                 unsigned int len = bvec->bv_len;
198 
199                 while (bh_offset(bh) < bvec->bv_offset)
200                         bh = bh->b_this_page;
201                 do {
202                         struct buffer_head *next = bh->b_this_page;
203                         len -= bh->b_size;
204                         bh->b_end_io(bh, !bio->bi_status);
205                         bh = next;
206                 } while (bh && len);
207         }
208         bio_put(bio);
209 }
210 
211 /*
212  * Submit several consecutive buffer head I/O requests as a single bio I/O
213  * request.  (See submit_bh_wbc.)
214  */
215 static void gfs2_submit_bhs(int op, int op_flags, struct buffer_head *bhs[],
216                             int num)
217 {
218         while (num > 0) {
219                 struct buffer_head *bh = *bhs;
220                 struct bio *bio;
221 
222                 bio = bio_alloc(GFP_NOIO, num);
223                 bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
224                 bio_set_dev(bio, bh->b_bdev);
225                 while (num > 0) {
226                         bh = *bhs;
227                         if (!bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh))) {
228                                 BUG_ON(bio->bi_iter.bi_size == 0);
229                                 break;
230                         }
231                         bhs++;
232                         num--;
233                 }
234                 bio->bi_end_io = gfs2_meta_read_endio;
235                 bio_set_op_attrs(bio, op, op_flags);
236                 submit_bio(bio);
237         }
238 }
239 
240 /**
241  * gfs2_meta_read - Read a block from disk
242  * @gl: The glock covering the block
243  * @blkno: The block number
244  * @flags: flags
245  * @bhp: the place where the buffer is returned (NULL on failure)
246  *
247  * Returns: errno
248  */
249 
250 int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
251                    int rahead, struct buffer_head **bhp)
252 {
253         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
254         struct buffer_head *bh, *bhs[2];
255         int num = 0;
256 
257         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
258                 *bhp = NULL;
259                 return -EIO;
260         }
261 
262         *bhp = bh = gfs2_getbuf(gl, blkno, CREATE);
263 
264         lock_buffer(bh);
265         if (buffer_uptodate(bh)) {
266                 unlock_buffer(bh);
267                 flags &= ~DIO_WAIT;
268         } else {
269                 bh->b_end_io = end_buffer_read_sync;
270                 get_bh(bh);
271                 bhs[num++] = bh;
272         }
273 
274         if (rahead) {
275                 bh = gfs2_getbuf(gl, blkno + 1, CREATE);
276 
277                 lock_buffer(bh);
278                 if (buffer_uptodate(bh)) {
279                         unlock_buffer(bh);
280                         brelse(bh);
281                 } else {
282                         bh->b_end_io = end_buffer_read_sync;
283                         bhs[num++] = bh;
284                 }
285         }
286 
287         gfs2_submit_bhs(REQ_OP_READ, REQ_META | REQ_PRIO, bhs, num);
288         if (!(flags & DIO_WAIT))
289                 return 0;
290 
291         bh = *bhp;
292         wait_on_buffer(bh);
293         if (unlikely(!buffer_uptodate(bh))) {
294                 struct gfs2_trans *tr = current->journal_info;
295                 if (tr && test_bit(TR_TOUCHED, &tr->tr_flags))
296                         gfs2_io_error_bh(sdp, bh);
297                 brelse(bh);
298                 *bhp = NULL;
299                 return -EIO;
300         }
301 
302         return 0;
303 }
304 
305 /**
306  * gfs2_meta_wait - Reread a block from disk
307  * @sdp: the filesystem
308  * @bh: The block to wait for
309  *
310  * Returns: errno
311  */
312 
313 int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
314 {
315         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
316                 return -EIO;
317 
318         wait_on_buffer(bh);
319 
320         if (!buffer_uptodate(bh)) {
321                 struct gfs2_trans *tr = current->journal_info;
322                 if (tr && test_bit(TR_TOUCHED, &tr->tr_flags))
323                         gfs2_io_error_bh(sdp, bh);
324                 return -EIO;
325         }
326         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
327                 return -EIO;
328 
329         return 0;
330 }
331 
332 void gfs2_remove_from_journal(struct buffer_head *bh, int meta)
333 {
334         struct address_space *mapping = bh->b_page->mapping;
335         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
336         struct gfs2_bufdata *bd = bh->b_private;
337         struct gfs2_trans *tr = current->journal_info;
338         int was_pinned = 0;
339 
340         if (test_clear_buffer_pinned(bh)) {
341                 trace_gfs2_pin(bd, 0);
342                 atomic_dec(&sdp->sd_log_pinned);
343                 list_del_init(&bd->bd_list);
344                 if (meta == REMOVE_META)
345                         tr->tr_num_buf_rm++;
346                 else
347                         tr->tr_num_databuf_rm++;
348                 set_bit(TR_TOUCHED, &tr->tr_flags);
349                 was_pinned = 1;
350                 brelse(bh);
351         }
352         if (bd) {
353                 spin_lock(&sdp->sd_ail_lock);
354                 if (bd->bd_tr) {
355                         gfs2_trans_add_revoke(sdp, bd);
356                 } else if (was_pinned) {
357                         bh->b_private = NULL;
358                         kmem_cache_free(gfs2_bufdata_cachep, bd);
359                 }
360                 spin_unlock(&sdp->sd_ail_lock);
361         }
362         clear_buffer_dirty(bh);
363         clear_buffer_uptodate(bh);
364 }
365 
366 /**
367  * gfs2_meta_wipe - make inode's buffers so they aren't dirty/pinned anymore
368  * @ip: the inode who owns the buffers
369  * @bstart: the first buffer in the run
370  * @blen: the number of buffers in the run
371  *
372  */
373 
374 void gfs2_meta_wipe(struct gfs2_inode *ip, u64 bstart, u32 blen)
375 {
376         struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
377         struct buffer_head *bh;
378 
379         while (blen) {
380                 bh = gfs2_getbuf(ip->i_gl, bstart, NO_CREATE);
381                 if (bh) {
382                         lock_buffer(bh);
383                         gfs2_log_lock(sdp);
384                         gfs2_remove_from_journal(bh, REMOVE_META);
385                         gfs2_log_unlock(sdp);
386                         unlock_buffer(bh);
387                         brelse(bh);
388                 }
389 
390                 bstart++;
391                 blen--;
392         }
393 }
394 
395 /**
396  * gfs2_meta_indirect_buffer - Get a metadata buffer
397  * @ip: The GFS2 inode
398  * @height: The level of this buf in the metadata (indir addr) tree (if any)
399  * @num: The block number (device relative) of the buffer
400  * @bhp: the buffer is returned here
401  *
402  * Returns: errno
403  */
404 
405 int gfs2_meta_indirect_buffer(struct gfs2_inode *ip, int height, u64 num,
406                               struct buffer_head **bhp)
407 {
408         struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
409         struct gfs2_glock *gl = ip->i_gl;
410         struct buffer_head *bh;
411         int ret = 0;
412         u32 mtype = height ? GFS2_METATYPE_IN : GFS2_METATYPE_DI;
413         int rahead = 0;
414 
415         if (num == ip->i_no_addr)
416                 rahead = ip->i_rahead;
417 
418         ret = gfs2_meta_read(gl, num, DIO_WAIT, rahead, &bh);
419         if (ret == 0 && gfs2_metatype_check(sdp, bh, mtype)) {
420                 brelse(bh);
421                 ret = -EIO;
422         } else {
423                 *bhp = bh;
424         }
425         return ret;
426 }
427 
428 /**
429  * gfs2_meta_ra - start readahead on an extent of a file
430  * @gl: the glock the blocks belong to
431  * @dblock: the starting disk block
432  * @extlen: the number of blocks in the extent
433  *
434  * returns: the first buffer in the extent
435  */
436 
437 struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)
438 {
439         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
440         struct buffer_head *first_bh, *bh;
441         u32 max_ra = gfs2_tune_get(sdp, gt_max_readahead) >>
442                           sdp->sd_sb.sb_bsize_shift;
443 
444         BUG_ON(!extlen);
445 
446         if (max_ra < 1)
447                 max_ra = 1;
448         if (extlen > max_ra)
449                 extlen = max_ra;
450 
451         first_bh = gfs2_getbuf(gl, dblock, CREATE);
452 
453         if (buffer_uptodate(first_bh))
454                 goto out;
455         if (!buffer_locked(first_bh))
456                 ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &first_bh);
457 
458         dblock++;
459         extlen--;
460 
461         while (extlen) {
462                 bh = gfs2_getbuf(gl, dblock, CREATE);
463 
464                 if (!buffer_uptodate(bh) && !buffer_locked(bh))
465                         ll_rw_block(REQ_OP_READ,
466                                     REQ_RAHEAD | REQ_META | REQ_PRIO,
467                                     1, &bh);
468                 brelse(bh);
469                 dblock++;
470                 extlen--;
471                 if (!buffer_locked(first_bh) && buffer_uptodate(first_bh))
472                         goto out;
473         }
474 
475         wait_on_buffer(first_bh);
476 out:
477         return first_bh;
478 }
479 
480 

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