diff options
Diffstat (limited to 'fs/ocfs2/buffer_head_io.c')
| -rw-r--r-- | fs/ocfs2/buffer_head_io.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c new file mode 100644 index 000000000..f9b84f7a3 --- /dev/null +++ b/fs/ocfs2/buffer_head_io.c @@ -0,0 +1,479 @@ +/* -*- mode: c; c-basic-offset: 8; -*- + * vim: noexpandtab sw=8 ts=8 sts=0: + * + * io.c + * + * Buffer cache handling + * + * Copyright (C) 2002, 2004 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include <linux/fs.h> +#include <linux/types.h> +#include <linux/highmem.h> +#include <linux/bio.h> + +#include <cluster/masklog.h> + +#include "ocfs2.h" + +#include "alloc.h" +#include "inode.h" +#include "journal.h" +#include "uptodate.h" +#include "buffer_head_io.h" +#include "ocfs2_trace.h" + +/* + * Bits on bh->b_state used by ocfs2. + * + * These MUST be after the JBD2 bits. Hence, we use BH_JBDPrivateStart. + */ +enum ocfs2_state_bits { + BH_NeedsValidate = BH_JBDPrivateStart, +}; + +/* Expand the magic b_state functions */ +BUFFER_FNS(NeedsValidate, needs_validate); + +int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh, + struct ocfs2_caching_info *ci) +{ + int ret = 0; + + trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci); + + BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO); + BUG_ON(buffer_jbd(bh)); + + /* No need to check for a soft readonly file system here. non + * journalled writes are only ever done on system files which + * can get modified during recovery even if read-only. */ + if (ocfs2_is_hard_readonly(osb)) { + ret = -EROFS; + mlog_errno(ret); + goto out; + } + + ocfs2_metadata_cache_io_lock(ci); + + lock_buffer(bh); + set_buffer_uptodate(bh); + + /* remove from dirty list before I/O. */ + clear_buffer_dirty(bh); + + get_bh(bh); /* for end_buffer_write_sync() */ + bh->b_end_io = end_buffer_write_sync; + submit_bh(REQ_OP_WRITE, 0, bh); + + wait_on_buffer(bh); + + if (buffer_uptodate(bh)) { + ocfs2_set_buffer_uptodate(ci, bh); + } else { + /* We don't need to remove the clustered uptodate + * information for this bh as it's not marked locally + * uptodate. */ + ret = -EIO; + mlog_errno(ret); + } + + ocfs2_metadata_cache_io_unlock(ci); +out: + return ret; +} + +/* Caller must provide a bhs[] with all NULL or non-NULL entries, so it + * will be easier to handle read failure. + */ +int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block, + unsigned int nr, struct buffer_head *bhs[]) +{ + int status = 0; + unsigned int i; + struct buffer_head *bh; + int new_bh = 0; + + trace_ocfs2_read_blocks_sync((unsigned long long)block, nr); + + if (!nr) + goto bail; + + /* Don't put buffer head and re-assign it to NULL if it is allocated + * outside since the caller can't be aware of this alternation! + */ + new_bh = (bhs[0] == NULL); + + for (i = 0 ; i < nr ; i++) { + if (bhs[i] == NULL) { + bhs[i] = sb_getblk(osb->sb, block++); + if (bhs[i] == NULL) { + status = -ENOMEM; + mlog_errno(status); + break; + } + } + bh = bhs[i]; + + if (buffer_jbd(bh)) { + trace_ocfs2_read_blocks_sync_jbd( + (unsigned long long)bh->b_blocknr); + continue; + } + + if (buffer_dirty(bh)) { + /* This should probably be a BUG, or + * at least return an error. */ + mlog(ML_ERROR, + "trying to sync read a dirty " + "buffer! (blocknr = %llu), skipping\n", + (unsigned long long)bh->b_blocknr); + continue; + } + + lock_buffer(bh); + if (buffer_jbd(bh)) { +#ifdef CATCH_BH_JBD_RACES + mlog(ML_ERROR, + "block %llu had the JBD bit set " + "while I was in lock_buffer!", + (unsigned long long)bh->b_blocknr); + BUG(); +#else + unlock_buffer(bh); + continue; +#endif + } + + get_bh(bh); /* for end_buffer_read_sync() */ + bh->b_end_io = end_buffer_read_sync; + submit_bh(REQ_OP_READ, 0, bh); + } + +read_failure: + for (i = nr; i > 0; i--) { + bh = bhs[i - 1]; + + if (unlikely(status)) { + if (new_bh && bh) { + /* If middle bh fails, let previous bh + * finish its read and then put it to + * aovoid bh leak + */ + if (!buffer_jbd(bh)) + wait_on_buffer(bh); + put_bh(bh); + bhs[i - 1] = NULL; + } else if (bh && buffer_uptodate(bh)) { + clear_buffer_uptodate(bh); + } + continue; + } + + /* No need to wait on the buffer if it's managed by JBD. */ + if (!buffer_jbd(bh)) + wait_on_buffer(bh); + + if (!buffer_uptodate(bh)) { + /* Status won't be cleared from here on out, + * so we can safely record this and loop back + * to cleanup the other buffers. */ + status = -EIO; + goto read_failure; + } + } + +bail: + return status; +} + +/* Caller must provide a bhs[] with all NULL or non-NULL entries, so it + * will be easier to handle read failure. + */ +int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr, + struct buffer_head *bhs[], int flags, + int (*validate)(struct super_block *sb, + struct buffer_head *bh)) +{ + int status = 0; + int i, ignore_cache = 0; + struct buffer_head *bh; + struct super_block *sb = ocfs2_metadata_cache_get_super(ci); + int new_bh = 0; + + trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags); + + BUG_ON(!ci); + BUG_ON((flags & OCFS2_BH_READAHEAD) && + (flags & OCFS2_BH_IGNORE_CACHE)); + + if (bhs == NULL) { + status = -EINVAL; + mlog_errno(status); + goto bail; + } + + if (nr < 0) { + mlog(ML_ERROR, "asked to read %d blocks!\n", nr); + status = -EINVAL; + mlog_errno(status); + goto bail; + } + + if (nr == 0) { + status = 0; + goto bail; + } + + /* Don't put buffer head and re-assign it to NULL if it is allocated + * outside since the caller can't be aware of this alternation! + */ + new_bh = (bhs[0] == NULL); + + ocfs2_metadata_cache_io_lock(ci); + for (i = 0 ; i < nr ; i++) { + if (bhs[i] == NULL) { + bhs[i] = sb_getblk(sb, block++); + if (bhs[i] == NULL) { + ocfs2_metadata_cache_io_unlock(ci); + status = -ENOMEM; + mlog_errno(status); + /* Don't forget to put previous bh! */ + break; + } + } + bh = bhs[i]; + ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE); + + /* There are three read-ahead cases here which we need to + * be concerned with. All three assume a buffer has + * previously been submitted with OCFS2_BH_READAHEAD + * and it hasn't yet completed I/O. + * + * 1) The current request is sync to disk. This rarely + * happens these days, and never when performance + * matters - the code can just wait on the buffer + * lock and re-submit. + * + * 2) The current request is cached, but not + * readahead. ocfs2_buffer_uptodate() will return + * false anyway, so we'll wind up waiting on the + * buffer lock to do I/O. We re-check the request + * with after getting the lock to avoid a re-submit. + * + * 3) The current request is readahead (and so must + * also be a caching one). We short circuit if the + * buffer is locked (under I/O) and if it's in the + * uptodate cache. The re-check from #2 catches the + * case that the previous read-ahead completes just + * before our is-it-in-flight check. + */ + + if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) { + trace_ocfs2_read_blocks_from_disk( + (unsigned long long)bh->b_blocknr, + (unsigned long long)ocfs2_metadata_cache_owner(ci)); + /* We're using ignore_cache here to say + * "go to disk" */ + ignore_cache = 1; + } + + trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr, + ignore_cache, buffer_jbd(bh), buffer_dirty(bh)); + + if (buffer_jbd(bh)) { + continue; + } + + if (ignore_cache) { + if (buffer_dirty(bh)) { + /* This should probably be a BUG, or + * at least return an error. */ + continue; + } + + /* A read-ahead request was made - if the + * buffer is already under read-ahead from a + * previously submitted request than we are + * done here. */ + if ((flags & OCFS2_BH_READAHEAD) + && ocfs2_buffer_read_ahead(ci, bh)) + continue; + + lock_buffer(bh); + if (buffer_jbd(bh)) { +#ifdef CATCH_BH_JBD_RACES + mlog(ML_ERROR, "block %llu had the JBD bit set " + "while I was in lock_buffer!", + (unsigned long long)bh->b_blocknr); + BUG(); +#else + unlock_buffer(bh); + continue; +#endif + } + + /* Re-check ocfs2_buffer_uptodate() as a + * previously read-ahead buffer may have + * completed I/O while we were waiting for the + * buffer lock. */ + if (!(flags & OCFS2_BH_IGNORE_CACHE) + && !(flags & OCFS2_BH_READAHEAD) + && ocfs2_buffer_uptodate(ci, bh)) { + unlock_buffer(bh); + continue; + } + + get_bh(bh); /* for end_buffer_read_sync() */ + if (validate) + set_buffer_needs_validate(bh); + bh->b_end_io = end_buffer_read_sync; + submit_bh(REQ_OP_READ, 0, bh); + continue; + } + } + +read_failure: + for (i = (nr - 1); i >= 0; i--) { + bh = bhs[i]; + + if (!(flags & OCFS2_BH_READAHEAD)) { + if (unlikely(status)) { + /* Clear the buffers on error including those + * ever succeeded in reading + */ + if (new_bh && bh) { + /* If middle bh fails, let previous bh + * finish its read and then put it to + * aovoid bh leak + */ + if (!buffer_jbd(bh)) + wait_on_buffer(bh); + put_bh(bh); + bhs[i] = NULL; + } else if (bh && buffer_uptodate(bh)) { + clear_buffer_uptodate(bh); + } + continue; + } + /* We know this can't have changed as we hold the + * owner sem. Avoid doing any work on the bh if the + * journal has it. */ + if (!buffer_jbd(bh)) + wait_on_buffer(bh); + + if (!buffer_uptodate(bh)) { + /* Status won't be cleared from here on out, + * so we can safely record this and loop back + * to cleanup the other buffers. Don't need to + * remove the clustered uptodate information + * for this bh as it's not marked locally + * uptodate. */ + status = -EIO; + clear_buffer_needs_validate(bh); + goto read_failure; + } + + if (buffer_needs_validate(bh)) { + /* We never set NeedsValidate if the + * buffer was held by the journal, so + * that better not have changed */ + BUG_ON(buffer_jbd(bh)); + clear_buffer_needs_validate(bh); + status = validate(sb, bh); + if (status) + goto read_failure; + } + } + + /* Always set the buffer in the cache, even if it was + * a forced read, or read-ahead which hasn't yet + * completed. */ + ocfs2_set_buffer_uptodate(ci, bh); + } + ocfs2_metadata_cache_io_unlock(ci); + + trace_ocfs2_read_blocks_end((unsigned long long)block, nr, + flags, ignore_cache); + +bail: + + return status; +} + +/* Check whether the blkno is the super block or one of the backups. */ +static void ocfs2_check_super_or_backup(struct super_block *sb, + sector_t blkno) +{ + int i; + u64 backup_blkno; + + if (blkno == OCFS2_SUPER_BLOCK_BLKNO) + return; + + for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) { + backup_blkno = ocfs2_backup_super_blkno(sb, i); + if (backup_blkno == blkno) + return; + } + + BUG(); +} + +/* + * Write super block and backups doesn't need to collaborate with journal, + * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed + * into this function. + */ +int ocfs2_write_super_or_backup(struct ocfs2_super *osb, + struct buffer_head *bh) +{ + int ret = 0; + struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data; + + BUG_ON(buffer_jbd(bh)); + ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr); + + if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) { + ret = -EROFS; + mlog_errno(ret); + goto out; + } + + lock_buffer(bh); + set_buffer_uptodate(bh); + + /* remove from dirty list before I/O. */ + clear_buffer_dirty(bh); + + get_bh(bh); /* for end_buffer_write_sync() */ + bh->b_end_io = end_buffer_write_sync; + ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check); + submit_bh(REQ_OP_WRITE, 0, bh); + + wait_on_buffer(bh); + + if (!buffer_uptodate(bh)) { + ret = -EIO; + mlog_errno(ret); + } + +out: + return ret; +} |