diff options
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 218 |
1 files changed, 114 insertions, 104 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index cc8452f60251..ead4dc85debd 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -176,18 +176,8 @@ void end_buffer_write_sync(struct buffer_head *bh, int uptodate) } EXPORT_SYMBOL(end_buffer_write_sync); -/* - * Various filesystems appear to want __find_get_block to be non-blocking. - * But it's the page lock which protects the buffers. To get around this, - * we get exclusion from try_to_free_buffers with the blockdev mapping's - * i_private_lock. - * - * Hack idea: for the blockdev mapping, i_private_lock contention - * may be quite high. This code could TryLock the page, and if that - * succeeds, there is no need to take i_private_lock. - */ static struct buffer_head * -__find_get_block_slow(struct block_device *bdev, sector_t block) +__find_get_block_slow(struct block_device *bdev, sector_t block, bool atomic) { struct address_space *bd_mapping = bdev->bd_mapping; const int blkbits = bd_mapping->host->i_blkbits; @@ -204,10 +194,28 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) if (IS_ERR(folio)) goto out; - spin_lock(&bd_mapping->i_private_lock); + /* + * Folio lock protects the buffers. Callers that cannot block + * will fallback to serializing vs try_to_free_buffers() via + * the i_private_lock. + */ + if (atomic) + spin_lock(&bd_mapping->i_private_lock); + else + folio_lock(folio); + head = folio_buffers(folio); if (!head) goto out_unlock; + /* + * Upon a noref migration, the folio lock serializes here; + * otherwise bail. + */ + if (test_bit_acquire(BH_Migrate, &head->b_state)) { + WARN_ON(!atomic); + goto out_unlock; + } + bh = head; do { if (!buffer_mapped(bh)) @@ -236,7 +244,10 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) 1 << blkbits); } out_unlock: - spin_unlock(&bd_mapping->i_private_lock); + if (atomic) + spin_unlock(&bd_mapping->i_private_lock); + else + folio_unlock(folio); folio_put(folio); out: return ret; @@ -286,7 +297,6 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate) still_busy: spin_unlock_irqrestore(&first->b_uptodate_lock, flags); - return; } struct postprocess_bh_ctx { @@ -411,7 +421,6 @@ static void end_buffer_async_write(struct buffer_head *bh, int uptodate) still_busy: spin_unlock_irqrestore(&first->b_uptodate_lock, flags); - return; } /* @@ -656,7 +665,9 @@ EXPORT_SYMBOL(generic_buffers_fsync); void write_boundary_block(struct block_device *bdev, sector_t bblock, unsigned blocksize) { - struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); + struct buffer_head *bh; + + bh = __find_get_block_nonatomic(bdev, bblock + 1, blocksize); if (bh) { if (buffer_dirty(bh)) write_dirty_buffer(bh, 0); @@ -1109,27 +1120,26 @@ static struct buffer_head * __getblk_slow(struct block_device *bdev, sector_t block, unsigned size, gfp_t gfp) { - /* Size must be multiple of hard sectorsize */ - if (unlikely(size & (bdev_logical_block_size(bdev)-1) || - (size < 512 || size > PAGE_SIZE))) { - printk(KERN_ERR "getblk(): invalid block size %d requested\n", - size); - printk(KERN_ERR "logical block size: %d\n", - bdev_logical_block_size(bdev)); + bool blocking = gfpflags_allow_blocking(gfp); - dump_stack(); + if (WARN_ON_ONCE(!IS_ALIGNED(size, bdev_logical_block_size(bdev)))) { + printk(KERN_ERR "getblk(): block size %d not aligned to logical block size %d\n", + size, bdev_logical_block_size(bdev)); return NULL; } for (;;) { struct buffer_head *bh; - bh = __find_get_block(bdev, block, size); - if (bh) - return bh; - if (!grow_buffers(bdev, block, size, gfp)) return NULL; + + if (blocking) + bh = __find_get_block_nonatomic(bdev, block, size); + else + bh = __find_get_block(bdev, block, size); + if (bh) + return bh; } } @@ -1207,10 +1217,8 @@ void mark_buffer_write_io_error(struct buffer_head *bh) /* FIXME: do we need to set this in both places? */ if (bh->b_folio && bh->b_folio->mapping) mapping_set_error(bh->b_folio->mapping, -EIO); - if (bh->b_assoc_map) { + if (bh->b_assoc_map) mapping_set_error(bh->b_assoc_map, -EIO); - errseq_set(&bh->b_assoc_map->host->i_sb->s_wb_err, -EIO); - } } EXPORT_SYMBOL(mark_buffer_write_io_error); @@ -1386,16 +1394,18 @@ lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) /* * Perform a pagecache lookup for the matching buffer. If it's there, refresh * it in the LRU and mark it as accessed. If it is not present then return - * NULL + * NULL. Atomic context callers may also return NULL if the buffer is being + * migrated; similarly the page is not marked accessed either. */ -struct buffer_head * -__find_get_block(struct block_device *bdev, sector_t block, unsigned size) +static struct buffer_head * +find_get_block_common(struct block_device *bdev, sector_t block, + unsigned size, bool atomic) { struct buffer_head *bh = lookup_bh_lru(bdev, block, size); if (bh == NULL) { /* __find_get_block_slow will mark the page accessed */ - bh = __find_get_block_slow(bdev, block); + bh = __find_get_block_slow(bdev, block, atomic); if (bh) bh_lru_install(bh); } else @@ -1403,8 +1413,23 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size) return bh; } + +struct buffer_head * +__find_get_block(struct block_device *bdev, sector_t block, unsigned size) +{ + return find_get_block_common(bdev, block, size, true); +} EXPORT_SYMBOL(__find_get_block); +/* same as __find_get_block() but allows sleeping contexts */ +struct buffer_head * +__find_get_block_nonatomic(struct block_device *bdev, sector_t block, + unsigned size) +{ + return find_get_block_common(bdev, block, size, false); +} +EXPORT_SYMBOL(__find_get_block_nonatomic); + /** * bdev_getblk - Get a buffer_head in a block device's buffer cache. * @bdev: The block device. @@ -1422,7 +1447,12 @@ EXPORT_SYMBOL(__find_get_block); struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block, unsigned size, gfp_t gfp) { - struct buffer_head *bh = __find_get_block(bdev, block, size); + struct buffer_head *bh; + + if (gfpflags_allow_blocking(gfp)) + bh = __find_get_block_nonatomic(bdev, block, size); + else + bh = __find_get_block(bdev, block, size); might_alloc(gfp); if (bh) @@ -1578,8 +1608,8 @@ static void discard_buffer(struct buffer_head * bh) bh->b_bdev = NULL; b_state = READ_ONCE(bh->b_state); do { - } while (!try_cmpxchg(&bh->b_state, &b_state, - b_state & ~BUFFER_FLAGS_DISCARD)); + } while (!try_cmpxchg_relaxed(&bh->b_state, &b_state, + b_state & ~BUFFER_FLAGS_DISCARD)); unlock_buffer(bh); } @@ -1644,7 +1674,6 @@ void block_invalidate_folio(struct folio *folio, size_t offset, size_t length) filemap_release_folio(folio, 0); out: folio_clear_mappedtodisk(folio); - return; } EXPORT_SYMBOL(block_invalidate_folio); @@ -2166,7 +2195,7 @@ int __block_write_begin(struct folio *folio, loff_t pos, unsigned len, } EXPORT_SYMBOL(__block_write_begin); -static void __block_commit_write(struct folio *folio, size_t from, size_t to) +void block_commit_write(struct folio *folio, size_t from, size_t to) { size_t block_start, block_end; bool partial = false; @@ -2204,6 +2233,7 @@ static void __block_commit_write(struct folio *folio, size_t from, size_t to) if (!partial) folio_mark_uptodate(folio); } +EXPORT_SYMBOL(block_commit_write); /* * block_write_begin takes care of the basic task of block allocation and @@ -2235,9 +2265,8 @@ int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, } EXPORT_SYMBOL(block_write_begin); -int block_write_end(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned copied, - struct folio *folio, void *fsdata) +int block_write_end(loff_t pos, unsigned len, unsigned copied, + struct folio *folio) { size_t start = pos - folio_pos(folio); @@ -2262,21 +2291,21 @@ int block_write_end(struct file *file, struct address_space *mapping, flush_dcache_folio(folio); /* This could be a short (even 0-length) commit */ - __block_commit_write(folio, start, start + copied); + block_commit_write(folio, start, start + copied); return copied; } EXPORT_SYMBOL(block_write_end); -int generic_write_end(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, unsigned copied, - struct folio *folio, void *fsdata) +int generic_write_end(const struct kiocb *iocb, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct folio *folio, void *fsdata) { struct inode *inode = mapping->host; loff_t old_size = inode->i_size; bool i_size_changed = false; - copied = block_write_end(file, mapping, pos, len, copied, folio, fsdata); + copied = block_write_end(pos, len, copied, folio); /* * No need to use i_size_read() here, the i_size cannot change under us @@ -2361,9 +2390,8 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) { struct inode *inode = folio->mapping->host; sector_t iblock, lblock; - struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; + struct buffer_head *bh, *head, *prev = NULL; size_t blocksize; - int nr, i; int fully_mapped = 1; bool page_error = false; loff_t limit = i_size_read(inode); @@ -2372,16 +2400,12 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode)) limit = inode->i_sb->s_maxbytes; - VM_BUG_ON_FOLIO(folio_test_large(folio), folio); - head = folio_create_buffers(folio, inode, 0); blocksize = head->b_size; iblock = div_u64(folio_pos(folio), blocksize); lblock = div_u64(limit + blocksize - 1, blocksize); bh = head; - nr = 0; - i = 0; do { if (buffer_uptodate(bh)) @@ -2398,7 +2422,7 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) page_error = true; } if (!buffer_mapped(bh)) { - folio_zero_range(folio, i * blocksize, + folio_zero_range(folio, bh_offset(bh), blocksize); if (!err) set_buffer_uptodate(bh); @@ -2411,40 +2435,33 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) if (buffer_uptodate(bh)) continue; } - arr[nr++] = bh; - } while (i++, iblock++, (bh = bh->b_this_page) != head); - - if (fully_mapped) - folio_set_mappedtodisk(folio); - - if (!nr) { - /* - * All buffers are uptodate or get_block() returned an - * error when trying to map them - we can finish the read. - */ - folio_end_read(folio, !page_error); - return 0; - } - /* Stage two: lock the buffers */ - for (i = 0; i < nr; i++) { - bh = arr[i]; lock_buffer(bh); + if (buffer_uptodate(bh)) { + unlock_buffer(bh); + continue; + } + mark_buffer_async_read(bh); - } + if (prev) + submit_bh(REQ_OP_READ, prev); + prev = bh; + } while (iblock++, (bh = bh->b_this_page) != head); + + if (fully_mapped) + folio_set_mappedtodisk(folio); /* - * Stage 3: start the IO. Check for uptodateness - * inside the buffer lock in case another process reading - * the underlying blockdev brought it uptodate (the sct fix). + * All buffers are uptodate or get_block() returned an error + * when trying to map them - we must finish the read because + * end_buffer_async_read() will never be called on any buffer + * in this folio. */ - for (i = 0; i < nr; i++) { - bh = arr[i]; - if (buffer_uptodate(bh)) - end_buffer_async_read(bh, 1); - else - submit_bh(REQ_OP_READ, bh); - } + if (prev) + submit_bh(REQ_OP_READ, prev); + else + folio_end_read(folio, !page_error); + return 0; } EXPORT_SYMBOL(block_read_full_folio); @@ -2477,7 +2494,8 @@ out: } EXPORT_SYMBOL(generic_cont_expand_simple); -static int cont_expand_zero(struct file *file, struct address_space *mapping, +static int cont_expand_zero(const struct kiocb *iocb, + struct address_space *mapping, loff_t pos, loff_t *bytes) { struct inode *inode = mapping->host; @@ -2501,12 +2519,12 @@ static int cont_expand_zero(struct file *file, struct address_space *mapping, } len = PAGE_SIZE - zerofrom; - err = aops->write_begin(file, mapping, curpos, len, + err = aops->write_begin(iocb, mapping, curpos, len, &folio, &fsdata); if (err) goto out; folio_zero_range(folio, offset_in_folio(folio, curpos), len); - err = aops->write_end(file, mapping, curpos, len, len, + err = aops->write_end(iocb, mapping, curpos, len, len, folio, fsdata); if (err < 0) goto out; @@ -2534,12 +2552,12 @@ static int cont_expand_zero(struct file *file, struct address_space *mapping, } len = offset - zerofrom; - err = aops->write_begin(file, mapping, curpos, len, + err = aops->write_begin(iocb, mapping, curpos, len, &folio, &fsdata); if (err) goto out; folio_zero_range(folio, offset_in_folio(folio, curpos), len); - err = aops->write_end(file, mapping, curpos, len, len, + err = aops->write_end(iocb, mapping, curpos, len, len, folio, fsdata); if (err < 0) goto out; @@ -2554,17 +2572,16 @@ out: * For moronic filesystems that do not allow holes in file. * We may have to extend the file. */ -int cont_write_begin(struct file *file, struct address_space *mapping, - loff_t pos, unsigned len, - struct folio **foliop, void **fsdata, - get_block_t *get_block, loff_t *bytes) +int cont_write_begin(const struct kiocb *iocb, struct address_space *mapping, + loff_t pos, unsigned len, struct folio **foliop, + void **fsdata, get_block_t *get_block, loff_t *bytes) { struct inode *inode = mapping->host; unsigned int blocksize = i_blocksize(inode); unsigned int zerofrom; int err; - err = cont_expand_zero(file, mapping, pos, bytes); + err = cont_expand_zero(iocb, mapping, pos, bytes); if (err) return err; @@ -2578,13 +2595,6 @@ int cont_write_begin(struct file *file, struct address_space *mapping, } EXPORT_SYMBOL(cont_write_begin); -void block_commit_write(struct page *page, unsigned from, unsigned to) -{ - struct folio *folio = page_folio(page); - __block_commit_write(folio, from, to); -} -EXPORT_SYMBOL(block_commit_write); - /* * block_page_mkwrite() is not allowed to change the file size as it gets * called from a page fault handler when a page is first dirtied. Hence we must @@ -2593,7 +2603,7 @@ EXPORT_SYMBOL(block_commit_write); * holes and correct delalloc and unwritten extent mapping on filesystems that * support these features. * - * We are not allowed to take the i_mutex here so we have to play games to + * We are not allowed to take the i_rwsem here so we have to play games to * protect against truncate races as the page could now be beyond EOF. Because * truncate writes the inode size before removing pages, once we have the * page lock we can determine safely if the page is beyond EOF. If it is not @@ -2630,7 +2640,7 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, if (unlikely(ret)) goto out_unlock; - __block_commit_write(folio, 0, end); + block_commit_write(folio, 0, end); folio_mark_dirty(folio); folio_wait_stable(folio); @@ -2713,7 +2723,7 @@ unlock: EXPORT_SYMBOL(block_truncate_page); /* - * The generic ->writepage function for buffer-backed address_spaces + * The generic write folio function for buffer-backed address_spaces */ int block_write_full_folio(struct folio *folio, struct writeback_control *wbc, void *get_block) @@ -2733,7 +2743,7 @@ int block_write_full_folio(struct folio *folio, struct writeback_control *wbc, /* * The folio straddles i_size. It must be zeroed out on each and every - * writepage invocation because it may be mmapped. "A file is mapped + * writeback invocation because it may be mmapped. "A file is mapped * in multiples of the page size. For a file that is not a multiple of * the page size, the remaining memory is zeroed when mapped, and * writes to that region are not written out to the file." |