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

---
fs/omfs/file.c | 346 ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++
1 file changed, 346 insertions(+)

Index: linux-2.6/fs/omfs/file.c
================================================== =================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/fs/omfs/file.c 2008-04-26 15:34:08.000000000 -0400
@@ -0,0 +1,346 @@
+/*
+ * OMFS (as used by RIO Karma) file operations.
+ * Copyright (C) 2005 Bob Copeland
+ * Released under GPL v2.
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include "omfs.h"
+
+static int omfs_sync_file(struct file *file, struct dentry *dentry,
+ int datasync)
+{
+ struct inode *inode = dentry->d_inode;
+ int err;
+
+ err = sync_mapping_buffers(inode->i_mapping);
+ if (!(inode->i_state & I_DIRTY))
+ return err;
+ if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
+ return err;
+ err |= omfs_sync_inode(inode);
+ return err ? -EIO : 0;
+}
+
+void omfs_make_empty_table(struct buffer_head *bh, int offset)
+{
+ struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
+
+ oe->e_next = ~0ULL;
+ oe->e_extent_count = cpu_to_be32(1),
+ oe->e_fill = cpu_to_be32(0x22),
+ oe->e_entry.e_cluster = ~0ULL;
+ oe->e_entry.e_blocks = ~0ULL;
+}
+
+int omfs_shrink_inode(struct inode *inode)
+{
+ struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+ struct omfs_extent *oe;
+ struct omfs_extent_entry *entry;
+ struct buffer_head *bh;
+ u64 next, last;
+ u32 extent_count;
+ int ret;
+
+ /* traverse extent table, freeing each entry that is greater
+ * than inode->i_size;
+ */
+ next = inode->i_ino;
+
+ /* only support truncate -> 0 for now */
+ ret = -EIO;
+ if (inode->i_size != 0)
+ goto out;
+
+ bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
+ if (!bh)
+ goto out;
+
+ oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
+
+ for (; {
+
+ if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) {
+ brelse(bh);
+ goto out;
+ }
+
+ extent_count = be32_to_cpu(oe->e_extent_count);
+ last = next;
+ next = be64_to_cpu(oe->e_next);
+ entry = &oe->e_entry;
+
+ /* ignore last entry as it is the terminator */
+ for (; extent_count > 1; extent_count--) {
+ u64 start, count;
+ start = be64_to_cpu(entry->e_cluster);
+ count = be64_to_cpu(entry->e_blocks);
+
+ omfs_clear_range(inode->i_sb, start, (int) count);
+ entry++;
+ }
+ omfs_make_empty_table(bh, (char *) oe - bh->b_data);
+ mark_buffer_dirty(bh);
+ brelse(bh);
+
+ if (last != inode->i_ino)
+ omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
+
+ if (next == ~0)
+ break;
+
+ bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
+ if (!bh)
+ goto out;
+ oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
+ }
+ ret = 0;
+out:
+ return ret;
+}
+
+static void omfs_truncate(struct inode *inode)
+{
+ omfs_shrink_inode(inode);
+ mark_inode_dirty(inode);
+}
+
+/*
+ * Add new blocks to the current extent, or create new entries/continuations
+ * as necessary.
+ */
+static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
+ u64 *ret_block)
+{
+ struct omfs_extent_entry *terminator;
+ struct omfs_extent_entry *entry = &oe->e_entry;
+ struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+ u32 extent_count = be32_to_cpu(oe->e_extent_count);
+ u64 new_block = 0;
+ u32 max_count;
+ int new_count;
+ int ret = 0;
+
+ /* reached the end of the extent table with no blocks mapped.
+ * there are three possibilities for adding: grow last extent,
+ * add a new extent to the current extent table, and add a
+ * continuation inode. in last two cases need an allocator for
+ * sbi->s_cluster_size
+ */
+
+ /* TODO: handle holes */
+
+ /* should always have a terminator */
+ if (extent_count < 1)
+ return -EIO;
+
+ /* trivially grow current extent, if next block is not taken */
+ terminator = entry + extent_count - 1;
+ if (extent_count > 1) {
+ entry = terminator-1;
+ new_block = be64_to_cpu(entry->e_cluster) +
+ be64_to_cpu(entry->e_blocks);
+
+ if (omfs_allocate_block(inode->i_sb, new_block)) {
+ entry->e_blocks =
+ cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
+ terminator->e_blocks = ~(cpu_to_be64(
+ be64_to_cpu(~terminator->e_blocks) + 1));
+ goto out;
+ }
+ }
+ max_count = (sbi->s_sys_blocksize - OMFS_EXTENT_START -
+ sizeof(struct omfs_extent)) /
+ sizeof(struct omfs_extent_entry) + 1;
+
+ /* TODO: add a continuation block here */
+ if (be32_to_cpu(oe->e_extent_count) > max_count-1)
+ return -EIO;
+
+ /* try to allocate a new cluster */
+ ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
+ &new_block, &new_count);
+ if (ret)
+ goto out_fail;
+
+ /* copy terminator down an entry */
+ entry = terminator;
+ terminator++;
+ memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
+
+ entry->e_cluster = cpu_to_be64(new_block);
+ entry->e_blocks = cpu_to_be64((u64) new_count);
+
+ terminator->e_blocks = ~(cpu_to_be64(
+ be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
+
+ /* write in new entry */
+ oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
+
+out:
+ *ret_block = new_block;
+out_fail:
+ return ret;
+}
+
+/*
+ * Scans across the directory table for a given file block number.
+ * If block not found, return 0.
+ */
+static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
+ sector_t block, int count, int *left)
+{
+ /* count > 1 because of terminator */
+ sector_t searched = 0;
+ for (; count > 1; count--) {
+ int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
+ be64_to_cpu(ent->e_blocks));
+
+ if (block >= searched &&
+ block < searched + numblocks) {
+ /*
+ * found it at cluster + (block - searched)
+ * numblocks - (block - searched) is remainder
+ */
+ *left = numblocks - (block - searched);
+ return clus_to_blk(OMFS_SB(inode->i_sb),
+ be64_to_cpu(ent->e_cluster)) +
+ block - searched;
+ }
+ searched += numblocks;
+ ent++;
+ }
+ return 0;
+}
+
+static int omfs_get_block(struct inode *inode, sector_t block,
+ struct buffer_head *bh_result, int create)
+{
+ struct buffer_head *bh;
+ sector_t next, offset;
+ int ret;
+ u64 new_block;
+ int extent_count;
+ struct omfs_extent *oe;
+ struct omfs_extent_entry *entry;
+ struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+ int max_blocks = bh_result->b_size >> inode->i_blkbits;
+ int remain;
+
+ ret = -EIO;
+ bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
+ if (!bh)
+ goto out;
+
+ oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
+ next = inode->i_ino;
+
+ for (; {
+
+ if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
+ goto out_brelse;
+
+ extent_count = be32_to_cpu(oe->e_extent_count);
+ next = be64_to_cpu(oe->e_next);
+ entry = &oe->e_entry;
+
+ offset = find_block(inode, entry, block, extent_count, &remain);
+ if (offset > 0) {
+ ret = 0;
+ map_bh(bh_result, inode->i_sb, offset);
+ if (remain > max_blocks)
+ remain = max_blocks;
+ bh_result->b_size = (remain << inode->i_blkbits);
+ goto out_brelse;
+ }
+ if (next == ~0)
+ break;
+
+ brelse(bh);
+ bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
+ if (!bh)
+ goto out;
+ oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
+ }
+ if (create) {
+ ret = omfs_grow_extent(inode, oe, &new_block);
+ if (ret == 0) {
+ mark_buffer_dirty(bh);
+ mark_inode_dirty(inode);
+ map_bh(bh_result, inode->i_sb,
+ clus_to_blk(sbi, new_block));
+ }
+ }
+out_brelse:
+ brelse(bh);
+out:
+ return ret;
+}
+
+static int omfs_readpage(struct file *file, struct page *page)
+{
+ return block_read_full_page(page, omfs_get_block);
+}
+
+static int omfs_readpages(struct file *file, struct address_space *mapping,
+ struct list_head *pages, unsigned nr_pages)
+{
+ return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
+}
+
+static int omfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ return block_write_full_page(page, omfs_get_block, wbc);
+}
+
+static int
+omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+ return mpage_writepages(mapping, wbc, omfs_get_block);
+}
+
+static int omfs_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata)
+{
+ *pagep = NULL;
+ return block_write_begin(file, mapping, pos, len, flags,
+ pagep, fsdata, omfs_get_block);
+}
+
+static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
+{
+ return generic_block_bmap(mapping, block, omfs_get_block);
+}
+
+struct file_operations omfs_file_operations = {
+ .llseek = generic_file_llseek,
+ .read = do_sync_read,
+ .write = do_sync_write,
+ .aio_read = generic_file_aio_read,
+ .aio_write = generic_file_aio_write,
+ .mmap = generic_file_mmap,
+ .fsync = omfs_sync_file,
+ .splice_read = generic_file_splice_read,
+};
+
+struct inode_operations omfs_file_inops = {
+ .truncate = omfs_truncate
+};
+
+struct address_space_operations omfs_aops = {
+ .readpage = omfs_readpage,
+ .readpages = omfs_readpages,
+ .writepage = omfs_writepage,
+ .writepages = omfs_writepages,
+ .sync_page = block_sync_page,
+ .write_begin = omfs_write_begin,
+ .write_end = generic_write_end,
+ .bmap = omfs_bmap,
+};
+

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