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

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