Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1408 insertions, 0 deletions

diff --git a/fs/reiserfs/file.c b/fs/reiserfs/file.c
new file mode 100644
index 0000000..2695011
--- /dev/null
+++ b/fs/reiserfs/file.c
@@ -0,0 +1,1408 @@
+/*
+ * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
+ */
+
+
+#include <linux/time.h>
+#include <linux/reiserfs_fs.h>
+#include <linux/reiserfs_acl.h>
+#include <linux/reiserfs_xattr.h>
+#include <linux/smp_lock.h>
+#include <asm/uaccess.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/quotaops.h>
+
+/*
+** We pack the tails of files on file close, not at the time they are written.
+** This implies an unnecessary copy of the tail and an unnecessary indirect item
+** insertion/balancing, for files that are written in one write.
+** It avoids unnecessary tail packings (balances) for files that are written in
+** multiple writes and are small enough to have tails.
+** 
+** file_release is called by the VFS layer when the file is closed.  If
+** this is the last open file descriptor, and the file
+** small enough to have a tail, and the tail is currently in an
+** unformatted node, the tail is converted back into a direct item.
+** 
+** We use reiserfs_truncate_file to pack the tail, since it already has
+** all the conditions coded.  
+*/
+static int reiserfs_file_release (struct inode * inode, struct file * filp)
+{
+
+    struct reiserfs_transaction_handle th ;
+    int err;
+    int jbegin_failure = 0;
+
+    if (!S_ISREG (inode->i_mode))
+	BUG ();
+
+    /* fast out for when nothing needs to be done */
+    if ((atomic_read(&inode->i_count) > 1 ||
+	!(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) || 
+         !tail_has_to_be_packed(inode))       && 
+	REISERFS_I(inode)->i_prealloc_count <= 0) {
+	return 0;
+    }    
+    
+    reiserfs_write_lock(inode->i_sb);
+    down (&inode->i_sem); 
+    /* freeing preallocation only involves relogging blocks that
+     * are already in the current transaction.  preallocation gets
+     * freed at the end of each transaction, so it is impossible for
+     * us to log any additional blocks (including quota blocks)
+     */
+    err = journal_begin(&th, inode->i_sb, 1);
+    if (err) {
+	/* uh oh, we can't allow the inode to go away while there
+	 * is still preallocation blocks pending.  Try to join the
+	 * aborted transaction
+	 */
+	jbegin_failure = err;
+	err = journal_join_abort(&th, inode->i_sb, 1);
+
+	if (err) {
+	    /* hmpf, our choices here aren't good.  We can pin the inode
+	     * which will disallow unmount from every happening, we can
+	     * do nothing, which will corrupt random memory on unmount,
+	     * or we can forcibly remove the file from the preallocation
+	     * list, which will leak blocks on disk.  Lets pin the inode
+	     * and let the admin know what is going on.
+	     */
+	    igrab(inode);
+	    reiserfs_warning(inode->i_sb, "pinning inode %lu because the "
+	                     "preallocation can't be freed");
+	    goto out;
+	}
+    }
+    reiserfs_update_inode_transaction(inode) ;
+
+#ifdef REISERFS_PREALLOCATE
+    reiserfs_discard_prealloc (&th, inode);
+#endif
+    err = journal_end(&th, inode->i_sb, 1);
+
+    /* copy back the error code from journal_begin */
+    if (!err)
+        err = jbegin_failure;
+
+    if (!err && atomic_read(&inode->i_count) <= 1 &&
+	(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) &&
+        tail_has_to_be_packed (inode)) {
+	/* if regular file is released by last holder and it has been
+	   appended (we append by unformatted node only) or its direct
+	   item(s) had to be converted, then it may have to be
+	   indirect2direct converted */
+	err = reiserfs_truncate_file(inode, 0) ;
+    }
+out:
+    up (&inode->i_sem); 
+    reiserfs_write_unlock(inode->i_sb);
+    return err;
+}
+
+static void reiserfs_vfs_truncate_file(struct inode *inode) {
+    reiserfs_truncate_file(inode, 1) ;
+}
+
+/* Sync a reiserfs file. */
+
+/*
+ * FIXME: sync_mapping_buffers() never has anything to sync.  Can
+ * be removed...
+ */
+
+static int reiserfs_sync_file(
+			      struct file   * p_s_filp,
+			      struct dentry * p_s_dentry,
+			      int datasync
+			      ) {
+  struct inode * p_s_inode = p_s_dentry->d_inode;
+  int n_err;
+  int barrier_done;
+
+  if (!S_ISREG(p_s_inode->i_mode))
+      BUG ();
+  n_err = sync_mapping_buffers(p_s_inode->i_mapping) ;
+  reiserfs_write_lock(p_s_inode->i_sb);
+  barrier_done = reiserfs_commit_for_inode(p_s_inode);
+  reiserfs_write_unlock(p_s_inode->i_sb);
+  if (barrier_done != 1)
+      blkdev_issue_flush(p_s_inode->i_sb->s_bdev, NULL);
+  if (barrier_done < 0)
+    return barrier_done;
+  return ( n_err < 0 ) ? -EIO : 0;
+}
+
+/* I really do not want to play with memory shortage right now, so
+   to simplify the code, we are not going to write more than this much pages at
+   a time. This still should considerably improve performance compared to 4k
+   at a time case. This is 32 pages of 4k size. */
+#define REISERFS_WRITE_PAGES_AT_A_TIME (128 * 1024) / PAGE_CACHE_SIZE
+
+/* Allocates blocks for a file to fulfil write request.
+   Maps all unmapped but prepared pages from the list.
+   Updates metadata with newly allocated blocknumbers as needed */
+static int reiserfs_allocate_blocks_for_region(
+				struct reiserfs_transaction_handle *th,
+				struct inode *inode, /* Inode we work with */
+				loff_t pos, /* Writing position */
+				int num_pages, /* number of pages write going
+						  to touch */
+				int write_bytes, /* amount of bytes to write */
+				struct page **prepared_pages, /* array of
+							         prepared pages
+							       */
+				int blocks_to_allocate /* Amount of blocks we
+							  need to allocate to
+							  fit the data into file
+							 */
+				)
+{
+    struct cpu_key key; // cpu key of item that we are going to deal with
+    struct item_head *ih; // pointer to item head that we are going to deal with
+    struct buffer_head *bh; // Buffer head that contains items that we are going to deal with
+    __u32 * item; // pointer to item we are going to deal with
+    INITIALIZE_PATH(path); // path to item, that we are going to deal with.
+    b_blocknr_t *allocated_blocks; // Pointer to a place where allocated blocknumbers would be stored.
+    reiserfs_blocknr_hint_t hint; // hint structure for block allocator.
+    size_t res; // return value of various functions that we call.
+    int curr_block; // current block used to keep track of unmapped blocks.
+    int i; // loop counter
+    int itempos; // position in item
+    unsigned int from = (pos & (PAGE_CACHE_SIZE - 1)); // writing position in
+						       // first page
+    unsigned int to = ((pos + write_bytes - 1) & (PAGE_CACHE_SIZE - 1)) + 1; /* last modified byte offset in last page */
+    __u64 hole_size ; // amount of blocks for a file hole, if it needed to be created.
+    int modifying_this_item = 0; // Flag for items traversal code to keep track
+				 // of the fact that we already prepared
+				 // current block for journal
+    int will_prealloc = 0;
+    RFALSE(!blocks_to_allocate, "green-9004: tried to allocate zero blocks?");
+
+    /* only preallocate if this is a small write */
+    if (REISERFS_I(inode)->i_prealloc_count ||
+       (!(write_bytes & (inode->i_sb->s_blocksize -1)) &&
+        blocks_to_allocate <
+        REISERFS_SB(inode->i_sb)->s_alloc_options.preallocsize))
+        will_prealloc = REISERFS_SB(inode->i_sb)->s_alloc_options.preallocsize;
+
+    allocated_blocks = kmalloc((blocks_to_allocate + will_prealloc) *
+    					sizeof(b_blocknr_t), GFP_NOFS);
+
+    /* First we compose a key to point at the writing position, we want to do
+       that outside of any locking region. */
+    make_cpu_key (&key, inode, pos+1, TYPE_ANY, 3/*key length*/);
+
+    /* If we came here, it means we absolutely need to open a transaction,
+       since we need to allocate some blocks */
+    reiserfs_write_lock(inode->i_sb); // Journaling stuff and we need that.
+    res = journal_begin(th, inode->i_sb, JOURNAL_PER_BALANCE_CNT * 3 + 1 + 2 * REISERFS_QUOTA_TRANS_BLOCKS); // Wish I know if this number enough
+    if (res)
+        goto error_exit;
+    reiserfs_update_inode_transaction(inode) ;
+
+    /* Look for the in-tree position of our write, need path for block allocator */
+    res = search_for_position_by_key(inode->i_sb, &key, &path);
+    if ( res == IO_ERROR ) {
+	res = -EIO;
+	goto error_exit;
+    }
+   
+    /* Allocate blocks */
+    /* First fill in "hint" structure for block allocator */
+    hint.th = th; // transaction handle.
+    hint.path = &path; // Path, so that block allocator can determine packing locality or whatever it needs to determine.
+    hint.inode = inode; // Inode is needed by block allocator too.
+    hint.search_start = 0; // We have no hint on where to search free blocks for block allocator.
+    hint.key = key.on_disk_key; // on disk key of file.
+    hint.block = inode->i_blocks>>(inode->i_sb->s_blocksize_bits-9); // Number of disk blocks this file occupies already.
+    hint.formatted_node = 0; // We are allocating blocks for unformatted node.
+    hint.preallocate = will_prealloc;
+
+    /* Call block allocator to allocate blocks */
+    res = reiserfs_allocate_blocknrs(&hint, allocated_blocks, blocks_to_allocate, blocks_to_allocate);
+    if ( res != CARRY_ON ) {
+	if ( res == NO_DISK_SPACE ) {
+	    /* We flush the transaction in case of no space. This way some
+	       blocks might become free */
+	    SB_JOURNAL(inode->i_sb)->j_must_wait = 1;
+	    res = restart_transaction(th, inode, &path);
+            if (res)
+                goto error_exit;
+
+	    /* We might have scheduled, so search again */
+	    res = search_for_position_by_key(inode->i_sb, &key, &path);
+	    if ( res == IO_ERROR ) {
+		res = -EIO;
+		goto error_exit;
+	    }
+
+	    /* update changed info for hint structure. */
+	    res = reiserfs_allocate_blocknrs(&hint, allocated_blocks, blocks_to_allocate, blocks_to_allocate);
+	    if ( res != CARRY_ON ) {
+		res = -ENOSPC; 
+		pathrelse(&path);
+		goto error_exit;
+	    }
+	} else {
+	    res = -ENOSPC;
+	    pathrelse(&path);
+	    goto error_exit;
+	}
+    }
+
+#ifdef __BIG_ENDIAN
+        // Too bad, I have not found any way to convert a given region from
+        // cpu format to little endian format
+    {
+        int i;
+        for ( i = 0; i < blocks_to_allocate ; i++)
+            allocated_blocks[i]=cpu_to_le32(allocated_blocks[i]);
+    }
+#endif
+
+    /* Blocks allocating well might have scheduled and tree might have changed,
+       let's search the tree again */
+    /* find where in the tree our write should go */
+    res = search_for_position_by_key(inode->i_sb, &key, &path);
+    if ( res == IO_ERROR ) {
+	res = -EIO;
+	goto error_exit_free_blocks;
+    }
+
+    bh = get_last_bh( &path ); // Get a bufferhead for last element in path.
+    ih = get_ih( &path );      // Get a pointer to last item head in path.
+    item = get_item( &path );  // Get a pointer to last item in path
+
+    /* Let's see what we have found */
+    if ( res != POSITION_FOUND ) { /* position not found, this means that we
+				      might need to append file with holes
+				      first */
+	// Since we are writing past the file's end, we need to find out if
+	// there is a hole that needs to be inserted before our writing
+	// position, and how many blocks it is going to cover (we need to
+	//  populate pointers to file blocks representing the hole with zeros)
+
+	{
+	    int item_offset = 1;
+	    /*
+	     * if ih is stat data, its offset is 0 and we don't want to
+	     * add 1 to pos in the hole_size calculation
+	     */
+	    if (is_statdata_le_ih(ih))
+	        item_offset = 0;
+	    hole_size = (pos + item_offset -
+	            (le_key_k_offset( get_inode_item_key_version(inode),
+		    &(ih->ih_key)) +
+		    op_bytes_number(ih, inode->i_sb->s_blocksize))) >>
+		    inode->i_sb->s_blocksize_bits;
+	}
+
+	if ( hole_size > 0 ) {
+	    int to_paste = min_t(__u64, hole_size, MAX_ITEM_LEN(inode->i_sb->s_blocksize)/UNFM_P_SIZE ); // How much data to insert first time.
+	    /* area filled with zeroes, to supply as list of zero blocknumbers
+	       We allocate it outside of loop just in case loop would spin for
+	       several iterations. */
+	    char *zeros = kmalloc(to_paste*UNFM_P_SIZE, GFP_ATOMIC); // We cannot insert more than MAX_ITEM_LEN bytes anyway.
+	    if ( !zeros ) {
+		res = -ENOMEM;
+		goto error_exit_free_blocks;
+	    }
+	    memset ( zeros, 0, to_paste*UNFM_P_SIZE);
+	    do {
+		to_paste = min_t(__u64, hole_size, MAX_ITEM_LEN(inode->i_sb->s_blocksize)/UNFM_P_SIZE );
+		if ( is_indirect_le_ih(ih) ) {
+		    /* Ok, there is existing indirect item already. Need to append it */
+		    /* Calculate position past inserted item */
+		    make_cpu_key( &key, inode, le_key_k_offset( get_inode_item_key_version(inode), &(ih->ih_key)) + op_bytes_number(ih, inode->i_sb->s_blocksize), TYPE_INDIRECT, 3);
+		    res = reiserfs_paste_into_item( th, &path, &key, inode, (char *)zeros, UNFM_P_SIZE*to_paste);
+		    if ( res ) {
+			kfree(zeros);
+			goto error_exit_free_blocks;
+		    }
+		} else if ( is_statdata_le_ih(ih) ) {
+		    /* No existing item, create it */
+		    /* item head for new item */
+		    struct item_head ins_ih;
+
+		    /* create a key for our new item */
+		    make_cpu_key( &key, inode, 1, TYPE_INDIRECT, 3);
+
+		    /* Create new item head for our new item */
+		    make_le_item_head (&ins_ih, &key, key.version, 1,
+				       TYPE_INDIRECT, to_paste*UNFM_P_SIZE,
+				       0 /* free space */);
+
+		    /* Find where such item should live in the tree */
+		    res = search_item (inode->i_sb, &key, &path);
+		    if ( res != ITEM_NOT_FOUND ) {
+			/* item should not exist, otherwise we have error */
+			if ( res != -ENOSPC ) {
+			    reiserfs_warning (inode->i_sb,
+				"green-9008: search_by_key (%K) returned %d",
+					      &key, res);
+			}
+			res = -EIO;
+		        kfree(zeros);
+			goto error_exit_free_blocks;
+		    }
+		    res = reiserfs_insert_item( th, &path, &key, &ins_ih, inode, (char *)zeros);
+		} else {
+		    reiserfs_panic(inode->i_sb, "green-9011: Unexpected key type %K\n", &key);
+		}
+		if ( res ) {
+		    kfree(zeros);
+		    goto error_exit_free_blocks;
+		}
+		/* Now we want to check if transaction is too full, and if it is
+		   we restart it. This will also free the path. */
+		if (journal_transaction_should_end(th, th->t_blocks_allocated)) {
+		    res = restart_transaction(th, inode, &path);
+                    if (res) {
+                        pathrelse (&path);
+                        kfree(zeros);
+                        goto error_exit;
+                    }
+                }
+
+		/* Well, need to recalculate path and stuff */
+		set_cpu_key_k_offset( &key, cpu_key_k_offset(&key) + (to_paste << inode->i_blkbits));
+		res = search_for_position_by_key(inode->i_sb, &key, &path);
+		if ( res == IO_ERROR ) {
+		    res = -EIO;
+		    kfree(zeros);
+		    goto error_exit_free_blocks;
+		}
+		bh=get_last_bh(&path);
+		ih=get_ih(&path);
+		item = get_item(&path);
+		hole_size -= to_paste;
+	    } while ( hole_size );
+	    kfree(zeros);
+	}
+    }
+
+    // Go through existing indirect items first
+    // replace all zeroes with blocknumbers from list
+    // Note that if no corresponding item was found, by previous search,
+    // it means there are no existing in-tree representation for file area
+    // we are going to overwrite, so there is nothing to scan through for holes.
+    for ( curr_block = 0, itempos = path.pos_in_item ; curr_block < blocks_to_allocate && res == POSITION_FOUND ; ) {
+retry:
+
+	if ( itempos >= ih_item_len(ih)/UNFM_P_SIZE ) {
+	    /* We run out of data in this indirect item, let's look for another
+	       one. */
+	    /* First if we are already modifying current item, log it */
+	    if ( modifying_this_item ) {
+		journal_mark_dirty (th, inode->i_sb, bh);
+		modifying_this_item = 0;
+	    }
+	    /* Then set the key to look for a new indirect item (offset of old
+	       item is added to old item length */
+	    set_cpu_key_k_offset( &key, le_key_k_offset( get_inode_item_key_version(inode), &(ih->ih_key)) + op_bytes_number(ih, inode->i_sb->s_blocksize));
+	    /* Search ofor position of new key in the tree. */
+	    res = search_for_position_by_key(inode->i_sb, &key, &path);
+	    if ( res == IO_ERROR) {
+		res = -EIO;
+		goto error_exit_free_blocks;
+	    }
+	    bh=get_last_bh(&path);
+	    ih=get_ih(&path);
+	    item = get_item(&path);
+	    itempos = path.pos_in_item;
+	    continue; // loop to check all kinds of conditions and so on.
+	}
+	/* Ok, we have correct position in item now, so let's see if it is
+	   representing file hole (blocknumber is zero) and fill it if needed */
+	if ( !item[itempos] ) {
+	    /* Ok, a hole. Now we need to check if we already prepared this
+	       block to be journaled */
+	    while ( !modifying_this_item ) { // loop until succeed
+		/* Well, this item is not journaled yet, so we must prepare
+		   it for journal first, before we can change it */
+		struct item_head tmp_ih; // We copy item head of found item,
+					 // here to detect if fs changed under
+					 // us while we were preparing for
+					 // journal.
+		int fs_gen; // We store fs generation here to find if someone
+			    // changes fs under our feet
+
+		copy_item_head (&tmp_ih, ih); // Remember itemhead
+		fs_gen = get_generation (inode->i_sb); // remember fs generation
+		reiserfs_prepare_for_journal(inode->i_sb, bh, 1); // Prepare a buffer within which indirect item is stored for changing.
+		if (fs_changed (fs_gen, inode->i_sb) && item_moved (&tmp_ih, &path)) {
+		    // Sigh, fs was changed under us, we need to look for new
+		    // location of item we are working with
+
+		    /* unmark prepaerd area as journaled and search for it's
+		       new position */
+		    reiserfs_restore_prepared_buffer(inode->i_sb, bh);
+		    res = search_for_position_by_key(inode->i_sb, &key, &path);
+		    if ( res == IO_ERROR) {
+			res = -EIO;
+			goto error_exit_free_blocks;
+		    }
+		    bh=get_last_bh(&path);
+		    ih=get_ih(&path);
+		    item = get_item(&path);
+		    itempos = path.pos_in_item;
+		    goto retry;
+		}
+		modifying_this_item = 1;
+	    }
+	    item[itempos] = allocated_blocks[curr_block]; // Assign new block
+	    curr_block++;
+	}
+	itempos++;
+    }
+
+    if ( modifying_this_item ) { // We need to log last-accessed block, if it
+				 // was modified, but not logged yet.
+	journal_mark_dirty (th, inode->i_sb, bh);
+    }
+
+    if ( curr_block < blocks_to_allocate ) {
+	// Oh, well need to append to indirect item, or to create indirect item
+	// if there weren't any
+	if ( is_indirect_le_ih(ih) ) {
+	    // Existing indirect item - append. First calculate key for append
+	    // position. We do not need to recalculate path as it should
+	    // already point to correct place.
+	    make_cpu_key( &key, inode, le_key_k_offset( get_inode_item_key_version(inode), &(ih->ih_key)) + op_bytes_number(ih, inode->i_sb->s_blocksize), TYPE_INDIRECT, 3);
+	    res = reiserfs_paste_into_item( th, &path, &key, inode, (char *)(allocated_blocks+curr_block), UNFM_P_SIZE*(blocks_to_allocate-curr_block));
+	    if ( res ) {
+		goto error_exit_free_blocks;
+	    }
+	} else if (is_statdata_le_ih(ih) ) {
+	    // Last found item was statdata. That means we need to create indirect item.
+	    struct item_head ins_ih; /* itemhead for new item */
+
+	    /* create a key for our new item */
+	    make_cpu_key( &key, inode, 1, TYPE_INDIRECT, 3); // Position one,
+							    // because that's
+							    // where first
+							    // indirect item
+							    // begins
+	    /* Create new item head for our new item */
+	    make_le_item_head (&ins_ih, &key, key.version, 1, TYPE_INDIRECT,
+			       (blocks_to_allocate-curr_block)*UNFM_P_SIZE,
+			       0 /* free space */);
+	    /* Find where such item should live in the tree */
+	    res = search_item (inode->i_sb, &key, &path);
+	    if ( res != ITEM_NOT_FOUND ) {
+		/* Well, if we have found such item already, or some error
+		   occured, we need to warn user and return error */
+		if ( res != -ENOSPC ) {
+		    reiserfs_warning (inode->i_sb,
+				      "green-9009: search_by_key (%K) "
+				      "returned %d", &key, res);
+		}
+		res = -EIO;
+		goto error_exit_free_blocks;
+	    }
+	    /* Insert item into the tree with the data as its body */
+	    res = reiserfs_insert_item( th, &path, &key, &ins_ih, inode, (char *)(allocated_blocks+curr_block));
+	} else {
+	    reiserfs_panic(inode->i_sb, "green-9010: unexpected item type for key %K\n",&key);
+	}
+    }
+
+    // the caller is responsible for closing the transaction
+    // unless we return an error, they are also responsible for logging
+    // the inode.
+    //
+    pathrelse(&path);
+    /*
+     * cleanup prellocation from previous writes
+     * if this is a partial block write
+     */
+    if (write_bytes & (inode->i_sb->s_blocksize -1))
+        reiserfs_discard_prealloc(th, inode);
+    reiserfs_write_unlock(inode->i_sb);
+
+    // go through all the pages/buffers and map the buffers to newly allocated
+    // blocks (so that system knows where to write these pages later).
+    curr_block = 0;
+    for ( i = 0; i < num_pages ; i++ ) {
+	struct page *page=prepared_pages[i]; //current page
+	struct buffer_head *head = page_buffers(page);// first buffer for a page
+	int block_start, block_end; // in-page offsets for buffers.
+
+	if (!page_buffers(page))
+	    reiserfs_panic(inode->i_sb, "green-9005: No buffers for prepared page???");
+
+	/* For each buffer in page */
+	for(bh = head, block_start = 0; bh != head || !block_start;
+	    block_start=block_end, bh = bh->b_this_page) {
+	    if (!bh)
+		reiserfs_panic(inode->i_sb, "green-9006: Allocated but absent buffer for a page?");
+	    block_end = block_start+inode->i_sb->s_blocksize;
+	    if (i == 0 && block_end <= from )
+		/* if this buffer is before requested data to map, skip it */
+		continue;
+	    if (i == num_pages - 1 && block_start >= to)
+		/* If this buffer is after requested data to map, abort
+		   processing of current page */
+		break;
+
+	    if ( !buffer_mapped(bh) ) { // Ok, unmapped buffer, need to map it
+		map_bh( bh, inode->i_sb, le32_to_cpu(allocated_blocks[curr_block]));
+		curr_block++;
+		set_buffer_new(bh);
+	    }
+	}
+    }
+
+    RFALSE( curr_block > blocks_to_allocate, "green-9007: Used too many blocks? weird");
+
+    kfree(allocated_blocks);
+    return 0;
+
+// Need to deal with transaction here.
+error_exit_free_blocks:
+    pathrelse(&path);
+    // free blocks
+    for( i = 0; i < blocks_to_allocate; i++ )
+	reiserfs_free_block(th, inode, le32_to_cpu(allocated_blocks[i]), 1);
+
+error_exit:
+    if (th->t_trans_id) {
+        int err;
+        // update any changes we made to blk count
+        reiserfs_update_sd(th, inode);
+        err = journal_end(th, inode->i_sb, JOURNAL_PER_BALANCE_CNT * 3 + 1 + 2 * REISERFS_QUOTA_TRANS_BLOCKS);
+        if (err)
+            res = err;
+    }
+    reiserfs_write_unlock(inode->i_sb);
+    kfree(allocated_blocks);
+
+    return res;
+}
+
+/* Unlock pages prepared by reiserfs_prepare_file_region_for_write */
+static void reiserfs_unprepare_pages(struct page **prepared_pages, /* list of locked pages */
+			      size_t num_pages /* amount of pages */) {
+    int i; // loop counter
+
+    for (i=0; i < num_pages ; i++) {
+	struct page *page = prepared_pages[i];
+
+	try_to_free_buffers(page);
+	unlock_page(page);
+	page_cache_release(page);
+    }
+}
+
+/* This function will copy data from userspace to specified pages within
+   supplied byte range */
+static int reiserfs_copy_from_user_to_file_region(
+				loff_t pos, /* In-file position */
+				int num_pages, /* Number of pages affected */
+				int write_bytes, /* Amount of bytes to write */
+				struct page **prepared_pages, /* pointer to 
+								 array to
+								 prepared pages
+								*/
+				const char __user *buf /* Pointer to user-supplied
+						   data*/
+				)
+{
+    long page_fault=0; // status of copy_from_user.
+    int i; // loop counter.
+    int offset; // offset in page
+
+    for ( i = 0, offset = (pos & (PAGE_CACHE_SIZE-1)); i < num_pages ; i++,offset=0) {
+	size_t count = min_t(size_t,PAGE_CACHE_SIZE-offset,write_bytes); // How much of bytes to write to this page
+	struct page *page=prepared_pages[i]; // Current page we process.
+
+	fault_in_pages_readable( buf, count);
+
+	/* Copy data from userspace to the current page */
+	kmap(page);
+	page_fault = __copy_from_user(page_address(page)+offset, buf, count); // Copy the data.
+	/* Flush processor's dcache for this page */
+	flush_dcache_page(page);
+	kunmap(page);
+	buf+=count;
+	write_bytes-=count;
+
+	if (page_fault)
+	    break; // Was there a fault? abort.
+    }
+
+    return page_fault?-EFAULT:0;
+}
+
+/* taken fs/buffer.c:__block_commit_write */
+int reiserfs_commit_page(struct inode *inode, struct page *page,
+		unsigned from, unsigned to)
+{
+    unsigned block_start, block_end;
+    int partial = 0;
+    unsigned blocksize;
+    struct buffer_head *bh, *head;
+    unsigned long i_size_index = inode->i_size >> PAGE_CACHE_SHIFT;
+    int new;
+    int logit = reiserfs_file_data_log(inode);
+    struct super_block *s = inode->i_sb;
+    int bh_per_page = PAGE_CACHE_SIZE / s->s_blocksize;
+    struct reiserfs_transaction_handle th;
+    int ret = 0;
+
+    th.t_trans_id = 0;
+    blocksize = 1 << inode->i_blkbits;
+
+    if (logit) {
+	reiserfs_write_lock(s);
+	ret = journal_begin(&th, s, bh_per_page + 1);
+	if (ret)
+	    goto drop_write_lock;
+	reiserfs_update_inode_transaction(inode);
+    }
+    for(bh = head = page_buffers(page), block_start = 0;
+        bh != head || !block_start;
+	block_start=block_end, bh = bh->b_this_page)
+    {
+
+	new = buffer_new(bh);
+	clear_buffer_new(bh);
+	block_end = block_start + blocksize;
+	if (block_end <= from || block_start >= to) {
+	    if (!buffer_uptodate(bh))
+		    partial = 1;
+	} else {
+	    set_buffer_uptodate(bh);
+	    if (logit) {
+		reiserfs_prepare_for_journal(s, bh, 1);
+		journal_mark_dirty(&th, s, bh);
+	    } else if (!buffer_dirty(bh)) {
+		mark_buffer_dirty(bh);
+		/* do data=ordered on any page past the end
+		 * of file and any buffer marked BH_New.
+		 */
+		if (reiserfs_data_ordered(inode->i_sb) &&
+		    (new || page->index >= i_size_index)) {
+		    reiserfs_add_ordered_list(inode, bh);
+	        }
+	    }
+	}
+    }
+    if (logit) {
+	ret = journal_end(&th, s, bh_per_page + 1);
+drop_write_lock:
+	reiserfs_write_unlock(s);
+    }
+    /*
+     * If this is a partial write which happened to make all buffers
+     * uptodate then we can optimize away a bogus readpage() for
+     * the next read(). Here we 'discover' whether the page went
+     * uptodate as a result of this (potentially partial) write.
+     */
+    if (!partial)
+	SetPageUptodate(page);
+    return ret;
+}
+
+
+/* Submit pages for write. This was separated from actual file copying
+   because we might want to allocate block numbers in-between.
+   This function assumes that caller will adjust file size to correct value. */
+static int reiserfs_submit_file_region_for_write(
+				struct reiserfs_transaction_handle *th,
+				struct inode *inode,
+				loff_t pos, /* Writing position offset */
+				size_t num_pages, /* Number of pages to write */
+				size_t write_bytes, /* number of bytes to write */
+				struct page **prepared_pages /* list of pages */
+				)
+{
+    int status; // return status of block_commit_write.
+    int retval = 0; // Return value we are going to return.
+    int i; // loop counter
+    int offset; // Writing offset in page.
+    int orig_write_bytes = write_bytes;
+    int sd_update = 0;
+
+    for ( i = 0, offset = (pos & (PAGE_CACHE_SIZE-1)); i < num_pages ; i++,offset=0) {
+	int count = min_t(int,PAGE_CACHE_SIZE-offset,write_bytes); // How much of bytes to write to this page
+	struct page *page=prepared_pages[i]; // Current page we process.
+
+	status = reiserfs_commit_page(inode, page, offset, offset+count);
+	if ( status )
+	    retval = status; // To not overcomplicate matters We are going to
+			     // submit all the pages even if there was error.
+			     // we only remember error status to report it on
+			     // exit.
+	write_bytes-=count;
+    }
+    /* now that we've gotten all the ordered buffers marked dirty,
+     * we can safely update i_size and close any running transaction
+     */
+    if ( pos + orig_write_bytes > inode->i_size) {
+	inode->i_size = pos + orig_write_bytes; // Set new size
+	/* If the file have grown so much that tail packing is no
+	 * longer possible, reset "need to pack" flag */
+	if ( (have_large_tails (inode->i_sb) &&
+	      inode->i_size > i_block_size (inode)*4) ||
+	     (have_small_tails (inode->i_sb) &&
+	     inode->i_size > i_block_size(inode)) )
+	    REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask ;
+        else if ( (have_large_tails (inode->i_sb) &&
+	          inode->i_size < i_block_size (inode)*4) ||
+	          (have_small_tails (inode->i_sb) &&
+		  inode->i_size < i_block_size(inode)) )
+	    REISERFS_I(inode)->i_flags |= i_pack_on_close_mask ;
+
+	if (th->t_trans_id) {
+	    reiserfs_write_lock(inode->i_sb);
+	    reiserfs_update_sd(th, inode); // And update on-disk metadata
+	    reiserfs_write_unlock(inode->i_sb);
+	} else
+	    inode->i_sb->s_op->dirty_inode(inode);
+
+        sd_update = 1;
+    }
+    if (th->t_trans_id) {
+	reiserfs_write_lock(inode->i_sb);
+	if (!sd_update)
+	    reiserfs_update_sd(th, inode);
+	status = journal_end(th, th->t_super, th->t_blocks_allocated);
+        if (status)
+            retval = status;
+	reiserfs_write_unlock(inode->i_sb);
+    }
+    th->t_trans_id = 0;
+
+    /* 
+     * we have to unlock the pages after updating i_size, otherwise
+     * we race with writepage
+     */
+    for ( i = 0; i < num_pages ; i++) {
+	struct page *page=prepared_pages[i];
+	unlock_page(page); 
+	mark_page_accessed(page);
+	page_cache_release(page);
+    }
+    return retval;
+}
+
+/* Look if passed writing region is going to touch file's tail
+   (if it is present). And if it is, convert the tail to unformatted node */
+static int reiserfs_check_for_tail_and_convert( struct inode *inode, /* inode to deal with */
+					 loff_t pos, /* Writing position */
+					 int write_bytes /* amount of bytes to write */
+				        )
+{
+    INITIALIZE_PATH(path); // needed for search_for_position
+    struct cpu_key key; // Key that would represent last touched writing byte.
+    struct item_head *ih; // item header of found block;
+    int res; // Return value of various functions we call.
+    int cont_expand_offset; // We will put offset for generic_cont_expand here
+			    // This can be int just because tails are created
+			    // only for small files.
+ 
+/* this embodies a dependency on a particular tail policy */
+    if ( inode->i_size >= inode->i_sb->s_blocksize*4 ) {
+	/* such a big files do not have tails, so we won't bother ourselves
+	   to look for tails, simply return */
+	return 0;
+    }
+
+    reiserfs_write_lock(inode->i_sb);
+    /* find the item containing the last byte to be written, or if
+     * writing past the end of the file then the last item of the
+     * file (and then we check its type). */
+    make_cpu_key (&key, inode, pos+write_bytes+1, TYPE_ANY, 3/*key length*/);
+    res = search_for_position_by_key(inode->i_sb, &key, &path);
+    if ( res == IO_ERROR ) {
+        reiserfs_write_unlock(inode->i_sb);
+	return -EIO;
+    }
+    ih = get_ih(&path);
+    res = 0;
+    if ( is_direct_le_ih(ih) ) {
+	/* Ok, closest item is file tail (tails are stored in "direct"
+	 * items), so we need to unpack it. */
+	/* To not overcomplicate matters, we just call generic_cont_expand
+	   which will in turn call other stuff and finally will boil down to
+	    reiserfs_get_block() that would do necessary conversion. */
+	cont_expand_offset = le_key_k_offset(get_inode_item_key_version(inode), &(ih->ih_key));
+	pathrelse(&path);
+	res = generic_cont_expand( inode, cont_expand_offset);
+    } else
+	pathrelse(&path);
+
+    reiserfs_write_unlock(inode->i_sb);
+    return res;
+}
+
+/* This function locks pages starting from @pos for @inode.
+   @num_pages pages are locked and stored in
+   @prepared_pages array. Also buffers are allocated for these pages.
+   First and last page of the region is read if it is overwritten only
+   partially. If last page did not exist before write (file hole or file
+   append), it is zeroed, then. 
+   Returns number of unallocated blocks that should be allocated to cover
+   new file data.*/
+static int reiserfs_prepare_file_region_for_write(
+				struct inode *inode /* Inode of the file */,
+				loff_t pos, /* position in the file */
+				size_t num_pages, /* number of pages to
+					          prepare */
+				size_t write_bytes, /* Amount of bytes to be
+						    overwritten from
+						    @pos */
+				struct page **prepared_pages /* pointer to array
+							       where to store
+							       prepared pages */
+					   )
+{
+    int res=0; // Return values of different functions we call.
+    unsigned long index = pos >> PAGE_CACHE_SHIFT; // Offset in file in pages.
+    int from = (pos & (PAGE_CACHE_SIZE - 1)); // Writing offset in first page
+    int to = ((pos + write_bytes - 1) & (PAGE_CACHE_SIZE - 1)) + 1;
+					 /* offset of last modified byte in last
+				            page */
+    struct address_space *mapping = inode->i_mapping; // Pages are mapped here.
+    int i; // Simple counter
+    int blocks = 0; /* Return value (blocks that should be allocated) */
+    struct buffer_head *bh, *head; // Current bufferhead and first bufferhead
+				   // of a page.
+    unsigned block_start, block_end; // Starting and ending offsets of current
+				     // buffer in the page.
+    struct buffer_head *wait[2], **wait_bh=wait; // Buffers for page, if
+						 // Page appeared to be not up
+						 // to date. Note how we have
+						 // at most 2 buffers, this is
+						 // because we at most may
+						 // partially overwrite two
+						 // buffers for one page. One at                                                 // the beginning of write area
+						 // and one at the end.
+						 // Everything inthe middle gets                                                 // overwritten totally.
+
+    struct cpu_key key; // cpu key of item that we are going to deal with
+    struct item_head *ih = NULL; // pointer to item head that we are going to deal with
+    struct buffer_head *itembuf=NULL; // Buffer head that contains items that we are going to deal with
+    INITIALIZE_PATH(path); // path to item, that we are going to deal with.
+    __u32 * item=NULL; // pointer to item we are going to deal with
+    int item_pos=-1; /* Position in indirect item */
+
+
+    if ( num_pages < 1 ) {
+	reiserfs_warning (inode->i_sb,
+			  "green-9001: reiserfs_prepare_file_region_for_write "
+			  "called with zero number of pages to process");
+	return -EFAULT;
+    }
+
+    /* We have 2 loops for pages. In first loop we grab and lock the pages, so
+       that nobody would touch these until we release the pages. Then
+       we'd start to deal with mapping buffers to blocks. */
+    for ( i = 0; i < num_pages; i++) {
+	prepared_pages[i] = grab_cache_page(mapping, index + i); // locks the page
+	if ( !prepared_pages[i]) {
+	    res = -ENOMEM;
+	    goto failed_page_grabbing;
+	}
+	if (!page_has_buffers(prepared_pages[i]))
+	    create_empty_buffers(prepared_pages[i], inode->i_sb->s_blocksize, 0);
+    }
+
+    /* Let's count amount of blocks for a case where all the blocks
+       overwritten are new (we will substract already allocated blocks later)*/
+    if ( num_pages > 2 )
+	/* These are full-overwritten pages so we count all the blocks in
+	   these pages are counted as needed to be allocated */
+	blocks = (num_pages - 2) << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+    /* count blocks needed for first page (possibly partially written) */
+    blocks += ((PAGE_CACHE_SIZE - from) >> inode->i_blkbits) +
+	   !!(from & (inode->i_sb->s_blocksize-1)); /* roundup */
+
+    /* Now we account for last page. If last page == first page (we
+       overwrite only one page), we substract all the blocks past the
+       last writing position in a page out of already calculated number
+       of blocks */
+    blocks += ((num_pages > 1) << (PAGE_CACHE_SHIFT-inode->i_blkbits)) -
+	   ((PAGE_CACHE_SIZE - to) >> inode->i_blkbits);
+	   /* Note how we do not roundup here since partial blocks still
+		   should be allocated */
+
+    /* Now if all the write area lies past the file end, no point in
+       maping blocks, since there is none, so we just zero out remaining
+       parts of first and last pages in write area (if needed) */
+    if ( (pos & ~((loff_t)PAGE_CACHE_SIZE - 1)) > inode->i_size ) {
+	if ( from != 0 ) {/* First page needs to be partially zeroed */
+	    char *kaddr = kmap_atomic(prepared_pages[0], KM_USER0);
+	    memset(kaddr, 0, from);
+	    kunmap_atomic( kaddr, KM_USER0);
+	}
+	if ( to != PAGE_CACHE_SIZE ) { /* Last page needs to be partially zeroed */
+	    char *kaddr = kmap_atomic(prepared_pages[num_pages-1], KM_USER0);
+	    memset(kaddr+to, 0, PAGE_CACHE_SIZE - to);
+	    kunmap_atomic( kaddr, KM_USER0);
+	}
+
+	/* Since all blocks are new - use already calculated value */
+	return blocks;
+    }
+
+    /* Well, since we write somewhere into the middle of a file, there is
+       possibility we are writing over some already allocated blocks, so
+       let's map these blocks and substract number of such blocks out of blocks
+       we need to allocate (calculated above) */
+    /* Mask write position to start on blocksize, we do it out of the
+       loop for performance reasons */
+    pos &= ~((loff_t) inode->i_sb->s_blocksize - 1);
+    /* Set cpu key to the starting position in a file (on left block boundary)*/
+    make_cpu_key (&key, inode, 1 + ((pos) & ~((loff_t) inode->i_sb->s_blocksize - 1)), TYPE_ANY, 3/*key length*/);
+
+    reiserfs_write_lock(inode->i_sb); // We need that for at least search_by_key()
+    for ( i = 0; i < num_pages ; i++ ) { 
+
+	head = page_buffers(prepared_pages[i]);
+	/* For each buffer in the page */
+	for(bh = head, block_start = 0; bh != head || !block_start;
+	    block_start=block_end, bh = bh->b_this_page) {
+		if (!bh)
+		    reiserfs_panic(inode->i_sb, "green-9002: Allocated but absent buffer for a page?");
+		/* Find where this buffer ends */
+		block_end = block_start+inode->i_sb->s_blocksize;
+		if (i == 0 && block_end <= from )
+		    /* if this buffer is before requested data to map, skip it*/
+		    continue;
+
+		if (i == num_pages - 1 && block_start >= to) {
+		    /* If this buffer is after requested data to map, abort
+		       processing of current page */
+		    break;
+		}
+
+		if ( buffer_mapped(bh) && bh->b_blocknr !=0 ) {
+		    /* This is optimisation for a case where buffer is mapped
+		       and have blocknumber assigned. In case significant amount
+		       of such buffers are present, we may avoid some amount
+		       of search_by_key calls.
+		       Probably it would be possible to move parts of this code
+		       out of BKL, but I afraid that would overcomplicate code
+		       without any noticeable benefit.
+		    */
+		    item_pos++;
+		    /* Update the key */
+		    set_cpu_key_k_offset( &key, cpu_key_k_offset(&key) + inode->i_sb->s_blocksize);
+		    blocks--; // Decrease the amount of blocks that need to be
+			      // allocated
+		    continue; // Go to the next buffer
+		}
+
+		if ( !itembuf || /* if first iteration */
+		     item_pos >= ih_item_len(ih)/UNFM_P_SIZE)
+					     { /* or if we progressed past the
+						  current unformatted_item */
+			/* Try to find next item */
+			res = search_for_position_by_key(inode->i_sb, &key, &path);
+			/* Abort if no more items */
+			if ( res != POSITION_FOUND ) {
+			    /* make sure later loops don't use this item */
+			    itembuf = NULL;
+			    item = NULL;
+			    break;
+			}
+
+			/* Update information about current indirect item */
+			itembuf = get_last_bh( &path );
+			ih = get_ih( &path );
+			item = get_item( &path );
+			item_pos = path.pos_in_item;
+
+			RFALSE( !is_indirect_le_ih (ih), "green-9003: indirect item expected");
+		}
+
+		/* See if there is some block associated with the file
+		   at that position, map the buffer to this block */
+		if ( get_block_num(item,item_pos) ) {
+		    map_bh(bh, inode->i_sb, get_block_num(item,item_pos));
+		    blocks--; // Decrease the amount of blocks that need to be
+			      // allocated
+		}
+		item_pos++;
+		/* Update the key */
+		set_cpu_key_k_offset( &key, cpu_key_k_offset(&key) + inode->i_sb->s_blocksize);
+	}
+    }
+    pathrelse(&path); // Free the path
+    reiserfs_write_unlock(inode->i_sb);
+
+	/* Now zero out unmappend buffers for the first and last pages of
+	   write area or issue read requests if page is mapped. */
+	/* First page, see if it is not uptodate */
+	if ( !PageUptodate(prepared_pages[0]) ) {
+	    head = page_buffers(prepared_pages[0]);
+
+	    /* For each buffer in page */
+	    for(bh = head, block_start = 0; bh != head || !block_start;
+		block_start=block_end, bh = bh->b_this_page) {
+
+		if (!bh)
+		    reiserfs_panic(inode->i_sb, "green-9002: Allocated but absent buffer for a page?");
+		/* Find where this buffer ends */
+		block_end = block_start+inode->i_sb->s_blocksize;
+		if ( block_end <= from )
+		    /* if this buffer is before requested data to map, skip it*/
+		    continue;
+		if ( block_start < from ) { /* Aha, our partial buffer */
+		    if ( buffer_mapped(bh) ) { /* If it is mapped, we need to
+						  issue READ request for it to
+						  not loose data */
+			ll_rw_block(READ, 1, &bh);
+			*wait_bh++=bh;
+		    } else { /* Not mapped, zero it */
+			char *kaddr = kmap_atomic(prepared_pages[0], KM_USER0);
+			memset(kaddr+block_start, 0, from-block_start);
+			kunmap_atomic( kaddr, KM_USER0);
+			set_buffer_uptodate(bh);
+		    }
+		}
+	    }
+	}
+
+	/* Last page, see if it is not uptodate, or if the last page is past the end of the file. */
+	if ( !PageUptodate(prepared_pages[num_pages-1]) || 
+	    ((pos+write_bytes)>>PAGE_CACHE_SHIFT) > (inode->i_size>>PAGE_CACHE_SHIFT) ) {
+	    head = page_buffers(prepared_pages[num_pages-1]);
+
+	    /* for each buffer in page */
+	    for(bh = head, block_start = 0; bh != head || !block_start;
+		block_start=block_end, bh = bh->b_this_page) {
+
+		if (!bh)
+		    reiserfs_panic(inode->i_sb, "green-9002: Allocated but absent buffer for a page?");
+		/* Find where this buffer ends */
+		block_end = block_start+inode->i_sb->s_blocksize;
+		if ( block_start >= to )
+		    /* if this buffer is after requested data to map, skip it*/
+		    break;
+		if ( block_end > to ) { /* Aha, our partial buffer */
+		    if ( buffer_mapped(bh) ) { /* If it is mapped, we need to
+						  issue READ request for it to
+						  not loose data */
+			ll_rw_block(READ, 1, &bh);
+			*wait_bh++=bh;
+		    } else { /* Not mapped, zero it */
+			char *kaddr = kmap_atomic(prepared_pages[num_pages-1], KM_USER0);
+			memset(kaddr+to, 0, block_end-to);
+			kunmap_atomic( kaddr, KM_USER0);
+			set_buffer_uptodate(bh);
+		    }
+		}
+	    }
+	}
+
+    /* Wait for read requests we made to happen, if necessary */
+    while(wait_bh > wait) {
+	wait_on_buffer(*--wait_bh);
+	if (!buffer_uptodate(*wait_bh)) {
+	    res = -EIO;
+	    goto failed_read;
+	}
+    }
+
+    return blocks;
+failed_page_grabbing:
+    num_pages = i;
+failed_read:
+    reiserfs_unprepare_pages(prepared_pages, num_pages);
+    return res;
+}
+
+/* Write @count bytes at position @ppos in a file indicated by @file
+   from the buffer @buf.  
+
+   generic_file_write() is only appropriate for filesystems that are not seeking to optimize performance and want
+   something simple that works.  It is not for serious use by general purpose filesystems, excepting the one that it was
+   written for (ext2/3).  This is for several reasons:
+
+   * It has no understanding of any filesystem specific optimizations.
+
+   * It enters the filesystem repeatedly for each page that is written.
+
+   * It depends on reiserfs_get_block() function which if implemented by reiserfs performs costly search_by_key
+   * operation for each page it is supplied with. By contrast reiserfs_file_write() feeds as much as possible at a time
+   * to reiserfs which allows for fewer tree traversals.
+
+   * Each indirect pointer insertion takes a lot of cpu, because it involves memory moves inside of blocks.
+
+   * Asking the block allocation code for blocks one at a time is slightly less efficient.
+
+   All of these reasons for not using only generic file write were understood back when reiserfs was first miscoded to
+   use it, but we were in a hurry to make code freeze, and so it couldn't be revised then.  This new code should make
+   things right finally.
+
+   Future Features: providing search_by_key with hints.
+
+*/
+static ssize_t reiserfs_file_write( struct file *file, /* the file we are going to write into */
+                             const char __user *buf, /*  pointer to user supplied data
+(in userspace) */
+                             size_t count, /* amount of bytes to write */
+                             loff_t *ppos /* pointer to position in file that we start writing at. Should be updated to
+                                           * new current position before returning. */ )
+{
+    size_t already_written = 0; // Number of bytes already written to the file.
+    loff_t pos; // Current position in the file.
+    ssize_t res; // return value of various functions that we call.
+    int err = 0;
+    struct inode *inode = file->f_dentry->d_inode; // Inode of the file that we are writing to.
+				/* To simplify coding at this time, we store
+				   locked pages in array for now */
+    struct page * prepared_pages[REISERFS_WRITE_PAGES_AT_A_TIME];
+    struct reiserfs_transaction_handle th;
+    th.t_trans_id = 0;
+
+    if ( file->f_flags & O_DIRECT) { // Direct IO needs treatment
+	ssize_t result, after_file_end = 0;
+	if ( (*ppos + count >= inode->i_size) || (file->f_flags & O_APPEND) ) {
+	    /* If we are appending a file, we need to put this savelink in here.
+	       If we will crash while doing direct io, finish_unfinished will
+	       cut the garbage from the file end. */
+	    reiserfs_write_lock(inode->i_sb);
+	    err = journal_begin(&th, inode->i_sb,  JOURNAL_PER_BALANCE_CNT );
+            if (err) {
+		reiserfs_write_unlock (inode->i_sb);
+		return err;
+	    }
+	    reiserfs_update_inode_transaction(inode);
+	    add_save_link (&th, inode, 1 /* Truncate */);
+	    after_file_end = 1;
+	    err = journal_end(&th, inode->i_sb, JOURNAL_PER_BALANCE_CNT );
+            reiserfs_write_unlock(inode->i_sb);
+	    if (err)
+		return err;
+	}
+	result = generic_file_write(file, buf, count, ppos);
+
+	if ( after_file_end ) { /* Now update i_size and remove the savelink */
+	    struct reiserfs_transaction_handle th;
+	    reiserfs_write_lock(inode->i_sb);
+	    err = journal_begin(&th, inode->i_sb, 1);
+            if (err) {
+                reiserfs_write_unlock (inode->i_sb);
+                return err;
+            }
+	    reiserfs_update_inode_transaction(inode);
+	    reiserfs_update_sd(&th, inode);
+	    err = journal_end(&th, inode->i_sb, 1);
+            if (err) {
+                reiserfs_write_unlock (inode->i_sb);
+                return err;
+            }
+	    err = remove_save_link (inode, 1/* truncate */);
+	    reiserfs_write_unlock(inode->i_sb);
+            if (err)
+                return err;
+	}
+
+	return result;
+    }
+
+    if ( unlikely((ssize_t) count < 0 ))
+        return -EINVAL;
+
+    if (unlikely(!access_ok(VERIFY_READ, buf, count)))
+        return -EFAULT;
+
+    down(&inode->i_sem); // locks the entire file for just us
+
+    pos = *ppos;
+
+    /* Check if we can write to specified region of file, file
+       is not overly big and this kind of stuff. Adjust pos and
+       count, if needed */
+    res = generic_write_checks(file, &pos, &count, 0);
+    if (res)
+	goto out;
+
+    if ( count == 0 )
+	goto out;
+
+    res = remove_suid(file->f_dentry);
+    if (res)
+	goto out;
+
+    inode_update_time(inode, 1); /* Both mtime and ctime */
+
+    // Ok, we are done with all the checks.
+
+    // Now we should start real work
+
+    /* If we are going to write past the file's packed tail or if we are going
+       to overwrite part of the tail, we need that tail to be converted into
+       unformatted node */
+    res = reiserfs_check_for_tail_and_convert( inode, pos, count);
+    if (res)
+	goto out;
+
+    while ( count > 0) {
+	/* This is the main loop in which we running until some error occures
+	   or until we write all of the data. */
+	size_t num_pages;/* amount of pages we are going to write this iteration */
+	size_t write_bytes; /* amount of bytes to write during this iteration */
+	size_t blocks_to_allocate; /* how much blocks we need to allocate for this iteration */
+        
+        /*  (pos & (PAGE_CACHE_SIZE-1)) is an idiom for offset into a page of pos*/
+	num_pages = !!((pos+count) & (PAGE_CACHE_SIZE - 1)) + /* round up partial
+							  pages */
+		    ((count + (pos & (PAGE_CACHE_SIZE-1))) >> PAGE_CACHE_SHIFT); 
+						/* convert size to amount of
+						   pages */
+	reiserfs_write_lock(inode->i_sb);
+	if ( num_pages > REISERFS_WRITE_PAGES_AT_A_TIME 
+		|| num_pages > reiserfs_can_fit_pages(inode->i_sb) ) {
+	    /* If we were asked to write more data than we want to or if there
+	       is not that much space, then we shorten amount of data to write
+	       for this iteration. */
+	    num_pages = min_t(size_t, REISERFS_WRITE_PAGES_AT_A_TIME, reiserfs_can_fit_pages(inode->i_sb));
+	    /* Also we should not forget to set size in bytes accordingly */
+	    write_bytes = (num_pages << PAGE_CACHE_SHIFT) - 
+			    (pos & (PAGE_CACHE_SIZE-1));
+					 /* If position is not on the
+					    start of the page, we need
+					    to substract the offset
+					    within page */
+	} else
+	    write_bytes = count;
+
+	/* reserve the blocks to be allocated later, so that later on
+	   we still have the space to write the blocks to */
+	reiserfs_claim_blocks_to_be_allocated(inode->i_sb, num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits));
+	reiserfs_write_unlock(inode->i_sb);
+
+	if ( !num_pages ) { /* If we do not have enough space even for */
+	    res = -ENOSPC;  /* single page, return -ENOSPC */
+	    if ( pos > (inode->i_size & (inode->i_sb->s_blocksize-1)))
+		break; // In case we are writing past the file end, break.
+	    // Otherwise we are possibly overwriting the file, so
+	    // let's set write size to be equal or less than blocksize.
+	    // This way we get it correctly for file holes.
+	    // But overwriting files on absolutelly full volumes would not
+	    // be very efficient. Well, people are not supposed to fill
+	    // 100% of disk space anyway.
+	    write_bytes = min_t(size_t, count, inode->i_sb->s_blocksize - (pos & (inode->i_sb->s_blocksize - 1)));
+	    num_pages = 1;
+	    // No blocks were claimed before, so do it now.
+	    reiserfs_claim_blocks_to_be_allocated(inode->i_sb, 1 << (PAGE_CACHE_SHIFT - inode->i_blkbits));
+	}
+
+	/* Prepare for writing into the region, read in all the
+	   partially overwritten pages, if needed. And lock the pages,
+	   so that nobody else can access these until we are done.
+	   We get number of actual blocks needed as a result.*/
+	blocks_to_allocate = reiserfs_prepare_file_region_for_write(inode, pos, num_pages, write_bytes, prepared_pages);
+	if ( blocks_to_allocate < 0 ) {
+	    res = blocks_to_allocate;
+	    reiserfs_release_claimed_blocks(inode->i_sb, num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits));
+	    break;
+	}
+
+	/* First we correct our estimate of how many blocks we need */
+	reiserfs_release_claimed_blocks(inode->i_sb, (num_pages << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits)) - blocks_to_allocate );
+
+	if ( blocks_to_allocate > 0) {/*We only allocate blocks if we need to*/
+	    /* Fill in all the possible holes and append the file if needed */
+	    res = reiserfs_allocate_blocks_for_region(&th, inode, pos, num_pages, write_bytes, prepared_pages, blocks_to_allocate);
+	}
+
+	/* well, we have allocated the blocks, so it is time to free
+	   the reservation we made earlier. */
+	reiserfs_release_claimed_blocks(inode->i_sb, blocks_to_allocate);
+	if ( res ) {
+	    reiserfs_unprepare_pages(prepared_pages, num_pages);
+	    break;
+	}
+
+/* NOTE that allocating blocks and filling blocks can be done in reverse order
+   and probably we would do that just to get rid of garbage in files after a
+   crash */
+
+	/* Copy data from user-supplied buffer to file's pages */
+	res = reiserfs_copy_from_user_to_file_region(pos, num_pages, write_bytes, prepared_pages, buf);
+	if ( res ) {
+	    reiserfs_unprepare_pages(prepared_pages, num_pages);
+	    break;
+	}
+
+	/* Send the pages to disk and unlock them. */
+	res = reiserfs_submit_file_region_for_write(&th, inode, pos, num_pages,
+	                                            write_bytes,prepared_pages);
+	if ( res )
+	    break;
+
+	already_written += write_bytes;
+	buf += write_bytes;
+	*ppos = pos += write_bytes;
+	count -= write_bytes;
+	balance_dirty_pages_ratelimited(inode->i_mapping);
+    }
+
+    /* this is only true on error */
+    if (th.t_trans_id) {
+        reiserfs_write_lock(inode->i_sb);
+        err = journal_end(&th, th.t_super, th.t_blocks_allocated);
+        reiserfs_write_unlock(inode->i_sb);
+        if (err) {
+            res = err;
+            goto out;
+        }
+    }
+
+    if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
+	res = generic_osync_inode(inode, file->f_mapping, OSYNC_METADATA|OSYNC_DATA);
+
+    up(&inode->i_sem);
+    reiserfs_async_progress_wait(inode->i_sb);
+    return (already_written != 0)?already_written:res;
+
+out:
+    up(&inode->i_sem); // unlock the file on exit.
+    return res;
+}
+
+static ssize_t reiserfs_aio_write(struct kiocb *iocb, const char __user *buf,
+			       size_t count, loff_t pos)
+{
+    return generic_file_aio_write(iocb, buf, count, pos);
+}
+
+
+
+struct file_operations reiserfs_file_operations = {
+    .read	= generic_file_read,
+    .write	= reiserfs_file_write,
+    .ioctl	= reiserfs_ioctl,
+    .mmap	= generic_file_mmap,
+    .release	= reiserfs_file_release,
+    .fsync	= reiserfs_sync_file,
+    .sendfile	= generic_file_sendfile,
+    .aio_read   = generic_file_aio_read,
+    .aio_write  = reiserfs_aio_write,
+};
+
+
+struct  inode_operations reiserfs_file_inode_operations = {
+    .truncate	= reiserfs_vfs_truncate_file,
+    .setattr    = reiserfs_setattr,
+    .setxattr   = reiserfs_setxattr,
+    .getxattr   = reiserfs_getxattr,
+    .listxattr  = reiserfs_listxattr,
+    .removexattr = reiserfs_removexattr,
+    .permission = reiserfs_permission,
+};
+
+