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omfs: add file routines
Add functions for reading and manipulating the storage of file data in the extent-based OMFS. Signed-off-by: Bob Copeland <me@bobcopeland.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bob Copeland
Linus Torvalds
parent
a3ab7155ea
commit
8f09e98768
1 changed files with 346 additions and 0 deletions
346
fs/omfs/file.c
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346
fs/omfs/file.c
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/*
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* OMFS (as used by RIO Karma) file operations.
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* Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
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* Released under GPL v2.
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*/
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#include <linux/version.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/mpage.h>
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#include "omfs.h"
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static int omfs_sync_file(struct file *file, struct dentry *dentry,
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int datasync)
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{
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struct inode *inode = dentry->d_inode;
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int err;
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err = sync_mapping_buffers(inode->i_mapping);
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if (!(inode->i_state & I_DIRTY))
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return err;
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if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
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return err;
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err |= omfs_sync_inode(inode);
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return err ? -EIO : 0;
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}
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void omfs_make_empty_table(struct buffer_head *bh, int offset)
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{
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struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
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oe->e_next = ~0ULL;
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oe->e_extent_count = cpu_to_be32(1),
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oe->e_fill = cpu_to_be32(0x22),
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oe->e_entry.e_cluster = ~0ULL;
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oe->e_entry.e_blocks = ~0ULL;
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}
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int omfs_shrink_inode(struct inode *inode)
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{
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struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
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struct omfs_extent *oe;
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struct omfs_extent_entry *entry;
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struct buffer_head *bh;
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u64 next, last;
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u32 extent_count;
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int ret;
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/* traverse extent table, freeing each entry that is greater
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* than inode->i_size;
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*/
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next = inode->i_ino;
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/* only support truncate -> 0 for now */
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ret = -EIO;
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if (inode->i_size != 0)
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goto out;
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bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
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if (!bh)
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goto out;
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oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
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for (;;) {
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if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) {
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brelse(bh);
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goto out;
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}
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extent_count = be32_to_cpu(oe->e_extent_count);
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last = next;
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next = be64_to_cpu(oe->e_next);
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entry = &oe->e_entry;
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/* ignore last entry as it is the terminator */
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for (; extent_count > 1; extent_count--) {
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u64 start, count;
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start = be64_to_cpu(entry->e_cluster);
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count = be64_to_cpu(entry->e_blocks);
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omfs_clear_range(inode->i_sb, start, (int) count);
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entry++;
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}
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omfs_make_empty_table(bh, (char *) oe - bh->b_data);
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mark_buffer_dirty(bh);
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brelse(bh);
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if (last != inode->i_ino)
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omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
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if (next == ~0)
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break;
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bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
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if (!bh)
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goto out;
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oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
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}
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ret = 0;
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out:
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return ret;
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}
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static void omfs_truncate(struct inode *inode)
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{
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omfs_shrink_inode(inode);
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mark_inode_dirty(inode);
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}
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/*
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* Add new blocks to the current extent, or create new entries/continuations
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* as necessary.
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*/
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static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
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u64 *ret_block)
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{
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struct omfs_extent_entry *terminator;
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struct omfs_extent_entry *entry = &oe->e_entry;
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struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
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u32 extent_count = be32_to_cpu(oe->e_extent_count);
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u64 new_block = 0;
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u32 max_count;
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int new_count;
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int ret = 0;
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/* reached the end of the extent table with no blocks mapped.
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* there are three possibilities for adding: grow last extent,
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* add a new extent to the current extent table, and add a
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* continuation inode. in last two cases need an allocator for
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* sbi->s_cluster_size
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*/
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/* TODO: handle holes */
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/* should always have a terminator */
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if (extent_count < 1)
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return -EIO;
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/* trivially grow current extent, if next block is not taken */
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terminator = entry + extent_count - 1;
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if (extent_count > 1) {
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entry = terminator-1;
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new_block = be64_to_cpu(entry->e_cluster) +
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be64_to_cpu(entry->e_blocks);
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if (omfs_allocate_block(inode->i_sb, new_block)) {
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entry->e_blocks =
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cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
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terminator->e_blocks = ~(cpu_to_be64(
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be64_to_cpu(~terminator->e_blocks) + 1));
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goto out;
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}
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}
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max_count = (sbi->s_sys_blocksize - OMFS_EXTENT_START -
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sizeof(struct omfs_extent)) /
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sizeof(struct omfs_extent_entry) + 1;
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/* TODO: add a continuation block here */
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if (be32_to_cpu(oe->e_extent_count) > max_count-1)
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return -EIO;
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/* try to allocate a new cluster */
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ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
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&new_block, &new_count);
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if (ret)
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goto out_fail;
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/* copy terminator down an entry */
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entry = terminator;
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terminator++;
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memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
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entry->e_cluster = cpu_to_be64(new_block);
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entry->e_blocks = cpu_to_be64((u64) new_count);
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terminator->e_blocks = ~(cpu_to_be64(
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be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
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/* write in new entry */
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oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
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out:
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*ret_block = new_block;
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out_fail:
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return ret;
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}
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/*
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* Scans across the directory table for a given file block number.
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* If block not found, return 0.
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*/
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static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
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sector_t block, int count, int *left)
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{
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/* count > 1 because of terminator */
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sector_t searched = 0;
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for (; count > 1; count--) {
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int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
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be64_to_cpu(ent->e_blocks));
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if (block >= searched &&
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block < searched + numblocks) {
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/*
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* found it at cluster + (block - searched)
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* numblocks - (block - searched) is remainder
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*/
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*left = numblocks - (block - searched);
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return clus_to_blk(OMFS_SB(inode->i_sb),
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be64_to_cpu(ent->e_cluster)) +
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block - searched;
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}
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searched += numblocks;
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ent++;
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}
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return 0;
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}
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static int omfs_get_block(struct inode *inode, sector_t block,
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struct buffer_head *bh_result, int create)
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{
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struct buffer_head *bh;
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sector_t next, offset;
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int ret;
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u64 new_block;
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int extent_count;
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struct omfs_extent *oe;
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struct omfs_extent_entry *entry;
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struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
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int max_blocks = bh_result->b_size >> inode->i_blkbits;
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int remain;
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ret = -EIO;
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bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
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if (!bh)
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goto out;
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oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
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next = inode->i_ino;
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for (;;) {
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if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
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goto out_brelse;
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extent_count = be32_to_cpu(oe->e_extent_count);
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next = be64_to_cpu(oe->e_next);
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entry = &oe->e_entry;
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offset = find_block(inode, entry, block, extent_count, &remain);
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if (offset > 0) {
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ret = 0;
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map_bh(bh_result, inode->i_sb, offset);
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if (remain > max_blocks)
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remain = max_blocks;
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bh_result->b_size = (remain << inode->i_blkbits);
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goto out_brelse;
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}
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if (next == ~0)
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break;
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brelse(bh);
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bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
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if (!bh)
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goto out;
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oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
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}
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if (create) {
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ret = omfs_grow_extent(inode, oe, &new_block);
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if (ret == 0) {
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mark_buffer_dirty(bh);
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mark_inode_dirty(inode);
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map_bh(bh_result, inode->i_sb,
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clus_to_blk(sbi, new_block));
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}
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}
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out_brelse:
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brelse(bh);
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out:
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return ret;
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}
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static int omfs_readpage(struct file *file, struct page *page)
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{
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return block_read_full_page(page, omfs_get_block);
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}
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static int omfs_readpages(struct file *file, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages)
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{
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return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
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}
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static int omfs_writepage(struct page *page, struct writeback_control *wbc)
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{
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return block_write_full_page(page, omfs_get_block, wbc);
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}
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static int
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omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
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{
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return mpage_writepages(mapping, wbc, omfs_get_block);
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}
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static int omfs_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata)
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{
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*pagep = NULL;
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return block_write_begin(file, mapping, pos, len, flags,
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pagep, fsdata, omfs_get_block);
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}
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static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
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{
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return generic_block_bmap(mapping, block, omfs_get_block);
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}
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struct file_operations omfs_file_operations = {
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.llseek = generic_file_llseek,
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.read = do_sync_read,
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.write = do_sync_write,
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.aio_read = generic_file_aio_read,
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.aio_write = generic_file_aio_write,
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.mmap = generic_file_mmap,
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.fsync = omfs_sync_file,
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.splice_read = generic_file_splice_read,
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};
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struct inode_operations omfs_file_inops = {
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.truncate = omfs_truncate
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};
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struct address_space_operations omfs_aops = {
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.readpage = omfs_readpage,
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.readpages = omfs_readpages,
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.writepage = omfs_writepage,
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.writepages = omfs_writepages,
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.sync_page = block_sync_page,
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.write_begin = omfs_write_begin,
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.write_end = generic_write_end,
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.bmap = omfs_bmap,
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};
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