fs/nilfs2/btnode.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * NILFS B-tree node cache
0004  *
0005  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
0006  *
0007  * Originally written by Seiji Kihara.
0008  * Fully revised by Ryusuke Konishi for stabilization and simplification.
0009  *
0010  */
0011
0012 #include <linux/types.h>
0013 #include <linux/buffer_head.h>
0014 #include <linux/mm.h>
0015 #include <linux/backing-dev.h>
0016 #include <linux/gfp.h>
0017 #include "nilfs.h"
0018 #include "mdt.h"
0019 #include "dat.h"
0020 #include "page.h"
0021 #include "btnode.h"
0022
0023
0024 /**
0025  * nilfs_init_btnc_inode - initialize B-tree node cache inode
0026  * @btnc_inode: inode to be initialized
0027  *
0028  * nilfs_init_btnc_inode() sets up an inode for B-tree node cache.
0029  */
0030 void nilfs_init_btnc_inode(struct inode *btnc_inode)
0031 {
0032     struct nilfs_inode_info *ii = NILFS_I(btnc_inode);
0033
0034     btnc_inode->i_mode = S_IFREG;
0035     ii->i_flags = 0;
0036     memset(&ii->i_bmap_data, 0, sizeof(struct nilfs_bmap));
0037     mapping_set_gfp_mask(btnc_inode->i_mapping, GFP_NOFS);
0038 }
0039
0040 void nilfs_btnode_cache_clear(struct address_space *btnc)
0041 {
0042     invalidate_mapping_pages(btnc, 0, -1);
0043     truncate_inode_pages(btnc, 0);
0044 }
0045
0046 struct buffer_head *
0047 nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
0048 {
0049     struct inode *inode = btnc->host;
0050     struct buffer_head *bh;
0051
0052     bh = nilfs_grab_buffer(inode, btnc, blocknr, BIT(BH_NILFS_Node));
0053     if (unlikely(!bh))
0054         return NULL;
0055
0056     if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
0057              buffer_dirty(bh))) {
0058         brelse(bh);
0059         BUG();
0060     }
0061     memset(bh->b_data, 0, i_blocksize(inode));
0062     bh->b_bdev = inode->i_sb->s_bdev;
0063     bh->b_blocknr = blocknr;
0064     set_buffer_mapped(bh);
0065     set_buffer_uptodate(bh);
0066
0067     unlock_page(bh->b_page);
0068     put_page(bh->b_page);
0069     return bh;
0070 }
0071
0072 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
0073                   sector_t pblocknr, blk_opf_t opf,
0074                   struct buffer_head **pbh, sector_t *submit_ptr)
0075 {
0076     struct buffer_head *bh;
0077     struct inode *inode = btnc->host;
0078     struct page *page;
0079     int err;
0080
0081     bh = nilfs_grab_buffer(inode, btnc, blocknr, BIT(BH_NILFS_Node));
0082     if (unlikely(!bh))
0083         return -ENOMEM;
0084
0085     err = -EEXIST; /* internal code */
0086     page = bh->b_page;
0087
0088     if (buffer_uptodate(bh) || buffer_dirty(bh))
0089         goto found;
0090
0091     if (pblocknr == 0) {
0092         pblocknr = blocknr;
0093         if (inode->i_ino != NILFS_DAT_INO) {
0094             struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
0095
0096             /* blocknr is a virtual block number */
0097             err = nilfs_dat_translate(nilfs->ns_dat, blocknr,
0098                           &pblocknr);
0099             if (unlikely(err)) {
0100                 brelse(bh);
0101                 goto out_locked;
0102             }
0103         }
0104     }
0105
0106     if (opf & REQ_RAHEAD) {
0107         if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
0108             err = -EBUSY; /* internal code */
0109             brelse(bh);
0110             goto out_locked;
0111         }
0112     } else { /* opf == REQ_OP_READ */
0113         lock_buffer(bh);
0114     }
0115     if (buffer_uptodate(bh)) {
0116         unlock_buffer(bh);
0117         err = -EEXIST; /* internal code */
0118         goto found;
0119     }
0120     set_buffer_mapped(bh);
0121     bh->b_bdev = inode->i_sb->s_bdev;
0122     bh->b_blocknr = pblocknr; /* set block address for read */
0123     bh->b_end_io = end_buffer_read_sync;
0124     get_bh(bh);
0125     submit_bh(opf, bh);
0126     bh->b_blocknr = blocknr; /* set back to the given block address */
0127     *submit_ptr = pblocknr;
0128     err = 0;
0129 found:
0130     *pbh = bh;
0131
0132 out_locked:
0133     unlock_page(page);
0134     put_page(page);
0135     return err;
0136 }
0137
0138 /**
0139  * nilfs_btnode_delete - delete B-tree node buffer
0140  * @bh: buffer to be deleted
0141  *
0142  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
0143  * including the buffer if the page gets unbusy.
0144  */
0145 void nilfs_btnode_delete(struct buffer_head *bh)
0146 {
0147     struct address_space *mapping;
0148     struct page *page = bh->b_page;
0149     pgoff_t index = page_index(page);
0150     int still_dirty;
0151
0152     get_page(page);
0153     lock_page(page);
0154     wait_on_page_writeback(page);
0155
0156     nilfs_forget_buffer(bh);
0157     still_dirty = PageDirty(page);
0158     mapping = page->mapping;
0159     unlock_page(page);
0160     put_page(page);
0161
0162     if (!still_dirty && mapping)
0163         invalidate_inode_pages2_range(mapping, index, index);
0164 }
0165
0166 /**
0167  * nilfs_btnode_prepare_change_key
0168  *  prepare to move contents of the block for old key to one of new key.
0169  *  the old buffer will not be removed, but might be reused for new buffer.
0170  *  it might return -ENOMEM because of memory allocation errors,
0171  *  and might return -EIO because of disk read errors.
0172  */
0173 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
0174                     struct nilfs_btnode_chkey_ctxt *ctxt)
0175 {
0176     struct buffer_head *obh, *nbh;
0177     struct inode *inode = btnc->host;
0178     __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
0179     int err;
0180
0181     if (oldkey == newkey)
0182         return 0;
0183
0184     obh = ctxt->bh;
0185     ctxt->newbh = NULL;
0186
0187     if (inode->i_blkbits == PAGE_SHIFT) {
0188         struct page *opage = obh->b_page;
0189         lock_page(opage);
0190 retry:
0191         /* BUG_ON(oldkey != obh->b_page->index); */
0192         if (unlikely(oldkey != opage->index))
0193             NILFS_PAGE_BUG(opage,
0194                        "invalid oldkey %lld (newkey=%lld)",
0195                        (unsigned long long)oldkey,
0196                        (unsigned long long)newkey);
0197
0198         xa_lock_irq(&btnc->i_pages);
0199         err = __xa_insert(&btnc->i_pages, newkey, opage, GFP_NOFS);
0200         xa_unlock_irq(&btnc->i_pages);
0201         /*
0202          * Note: page->index will not change to newkey until
0203          * nilfs_btnode_commit_change_key() will be called.
0204          * To protect the page in intermediate state, the page lock
0205          * is held.
0206          */
0207         if (!err)
0208             return 0;
0209         else if (err != -EBUSY)
0210             goto failed_unlock;
0211
0212         err = invalidate_inode_pages2_range(btnc, newkey, newkey);
0213         if (!err)
0214             goto retry;
0215         /* fallback to copy mode */
0216         unlock_page(opage);
0217     }
0218
0219     nbh = nilfs_btnode_create_block(btnc, newkey);
0220     if (!nbh)
0221         return -ENOMEM;
0222
0223     BUG_ON(nbh == obh);
0224     ctxt->newbh = nbh;
0225     return 0;
0226
0227  failed_unlock:
0228     unlock_page(obh->b_page);
0229     return err;
0230 }
0231
0232 /**
0233  * nilfs_btnode_commit_change_key
0234  *  commit the change_key operation prepared by prepare_change_key().
0235  */
0236 void nilfs_btnode_commit_change_key(struct address_space *btnc,
0237                     struct nilfs_btnode_chkey_ctxt *ctxt)
0238 {
0239     struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
0240     __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
0241     struct page *opage;
0242
0243     if (oldkey == newkey)
0244         return;
0245
0246     if (nbh == NULL) {  /* blocksize == pagesize */
0247         opage = obh->b_page;
0248         if (unlikely(oldkey != opage->index))
0249             NILFS_PAGE_BUG(opage,
0250                        "invalid oldkey %lld (newkey=%lld)",
0251                        (unsigned long long)oldkey,
0252                        (unsigned long long)newkey);
0253         mark_buffer_dirty(obh);
0254
0255         xa_lock_irq(&btnc->i_pages);
0256         __xa_erase(&btnc->i_pages, oldkey);
0257         __xa_set_mark(&btnc->i_pages, newkey, PAGECACHE_TAG_DIRTY);
0258         xa_unlock_irq(&btnc->i_pages);
0259
0260         opage->index = obh->b_blocknr = newkey;
0261         unlock_page(opage);
0262     } else {
0263         nilfs_copy_buffer(nbh, obh);
0264         mark_buffer_dirty(nbh);
0265
0266         nbh->b_blocknr = newkey;
0267         ctxt->bh = nbh;
0268         nilfs_btnode_delete(obh); /* will decrement bh->b_count */
0269     }
0270 }
0271
0272 /**
0273  * nilfs_btnode_abort_change_key
0274  *  abort the change_key operation prepared by prepare_change_key().
0275  */
0276 void nilfs_btnode_abort_change_key(struct address_space *btnc,
0277                    struct nilfs_btnode_chkey_ctxt *ctxt)
0278 {
0279     struct buffer_head *nbh = ctxt->newbh;
0280     __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
0281
0282     if (oldkey == newkey)
0283         return;
0284
0285     if (nbh == NULL) {  /* blocksize == pagesize */
0286         xa_erase_irq(&btnc->i_pages, newkey);
0287         unlock_page(ctxt->bh->b_page);
0288     } else
0289         brelse(nbh);
0290 }