patch-2.4.1 linux/fs/reiserfs/tail_conversion.c

• Lines: 298
• Date: Mon Jan 15 15:31:19 2001
• Orig file: v2.4.0/linux/fs/reiserfs/tail_conversion.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.0/linux/fs/reiserfs/tail_conversion.c linux/fs/reiserfs/tail_conversion.c
@@ -0,0 +1,297 @@
+/*
+ * Copyright 1999 Hans Reiser, see reiserfs/README for licensing and copyright details
+ */
+
+#ifdef __KERNEL__
+
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/pagemap.h>
+#include <linux/reiserfs_fs.h>
+#include <linux/locks.h>
+
+#else
+
+#include "nokernel.h"
+
+#endif
+
+
+/* access to tail : when one is going to read tail it must make sure, that is not running.
+ direct2indirect and indirect2direct can not run concurrently */
+
+
+/* Converts direct items to an unformatted node. Panics if file has no
+   tail. -ENOSPC if no disk space for conversion */
+/* path points to first direct item of the file regarless of how many of
+   them are there */
+int direct2indirect (struct reiserfs_transaction_handle *th, struct inode * inode, 
+		     struct path * path, struct buffer_head * unbh,
+		     loff_t tail_offset)
+{
+    struct super_block * sb = inode->i_sb;
+    struct buffer_head *up_to_date_bh ;
+    struct item_head * p_le_ih = PATH_PITEM_HEAD (path);
+    struct cpu_key end_key;  /* Key to search for the last byte of the
+				converted item. */
+    struct item_head ind_ih; /* new indirect item to be inserted or
+                                key of unfm pointer to be pasted */
+    int	n_blk_size,
+      n_retval;	  /* returned value for reiserfs_insert_item and clones */
+    struct unfm_nodeinfo unfm_ptr;  /* Handle on an unformatted node
+				       that will be inserted in the
+				       tree. */
+
+
+    sb->u.reiserfs_sb.s_direct2indirect ++;
+
+    n_blk_size = sb->s_blocksize;
+
+    /* and key to search for append or insert pointer to the new
+       unformatted node. */
+    copy_item_head (&ind_ih, p_le_ih);
+    set_le_ih_k_offset (&ind_ih, tail_offset);
+    set_le_ih_k_type (&ind_ih, TYPE_INDIRECT);
+
+    /* Set the key to search for the place for new unfm pointer */
+    make_cpu_key (&end_key, inode, tail_offset, TYPE_INDIRECT, 4);
+
+    // FIXME: we could avoid this 
+    if ( search_for_position_by_key (sb, &end_key, path) == POSITION_FOUND )
+	reiserfs_panic (sb, "PAP-14030: direct2indirect: "
+			"pasted or inserted byte exists in the tree");
+    
+    p_le_ih = PATH_PITEM_HEAD (path);
+
+    unfm_ptr.unfm_nodenum = cpu_to_le32 (unbh->b_blocknr);
+    unfm_ptr.unfm_freespace = 0; // ???
+    
+    if ( is_statdata_le_ih (p_le_ih) )  {
+	/* Insert new indirect item. */
+	set_ih_free_space (&ind_ih, 0); /* delete at nearest future */
+	ind_ih.ih_item_len = cpu_to_le16 (UNFM_P_SIZE);
+	PATH_LAST_POSITION (path)++;
+	n_retval = reiserfs_insert_item (th, path, &end_key, &ind_ih, 
+					 (char *)&unfm_ptr);
+    } else {
+	/* Paste into last indirect item of an object. */
+	n_retval = reiserfs_paste_into_item(th, path, &end_key,
+					    (char *)&unfm_ptr, UNFM_P_SIZE);
+    }
+    if ( n_retval ) {
+	return n_retval;
+    }
+
+    // note: from here there are two keys which have matching first
+    // three key components. They only differ by the fourth one.
+
+
+    /* Set the key to search for the direct items of the file */
+    make_cpu_key (&end_key, inode, max_reiserfs_offset (inode), TYPE_DIRECT, 4);
+
+    /* Move bytes from the direct items to the new unformatted node
+       and delete them. */
+    while (1)  {
+	int item_len, first_direct;
+
+	/* end_key.k_offset is set so, that we will always have found
+           last item of the file */
+	if ( search_for_position_by_key (sb, &end_key, path) == POSITION_FOUND )
+	    reiserfs_panic (sb, "PAP-14050: direct2indirect: "
+			    "direct item (%k) not found", &end_key);
+	p_le_ih = PATH_PITEM_HEAD (path);
+#ifdef CONFIG_REISERFS_CHECK
+	if (!is_direct_le_ih (p_le_ih))
+	    reiserfs_panic (sb, "vs-14055: direct2indirect: "
+			    "direct item expected, found %h", p_le_ih);
+#endif
+	if ((le_ih_k_offset (p_le_ih) & (n_blk_size - 1)) == 1)
+	    first_direct = 1;
+	else
+	    first_direct = 0;
+	item_len = le16_to_cpu (p_le_ih->ih_item_len);
+
+	/* we only send the unbh pointer if the buffer is not up to date.
+	** this avoids overwriting good data from writepage() with old data
+	** from the disk or buffer cache
+	*/
+	if (buffer_uptodate(unbh) || Page_Uptodate(unbh->b_page)) {
+	    up_to_date_bh = NULL ;
+	} else {
+	    up_to_date_bh = unbh ;
+	}
+	n_retval = reiserfs_delete_item (th, path, &end_key, inode, 
+	                                 up_to_date_bh) ;
+
+	if (first_direct && item_len == n_retval)
+	    // done: file does not have direct items anymore
+	    break;
+
+    }
+
+    inode->u.reiserfs_i.i_first_direct_byte = U32_MAX;
+
+    return 0;
+}
+
+
+/* stolen from fs/buffer.c */
+void reiserfs_unmap_buffer(struct buffer_head *bh) {
+  if (buffer_mapped(bh)) {
+    if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
+      BUG() ;
+    }
+    mark_buffer_clean(bh) ;
+    wait_on_buffer(bh) ;
+    // clear_bit(BH_Uptodate, &bh->b_state) ;
+    clear_bit(BH_Mapped, &bh->b_state) ;
+    clear_bit(BH_Req, &bh->b_state) ;
+    clear_bit(BH_New, &bh->b_state) ;
+  }
+}
+
+static void
+unmap_buffers(struct page *page, loff_t pos) {
+  struct buffer_head *bh ;
+  struct buffer_head *head ;
+  struct buffer_head *next ;
+  unsigned long tail_index ;
+  unsigned long cur_index ;
+
+  if (page) {
+    if (page->buffers) {
+      tail_index = pos & (PAGE_CACHE_SIZE - 1) ;
+      cur_index = 0 ;
+      head = page->buffers ;
+      bh = head ;
+      do {
+	next = bh->b_this_page ;
+
+        /* we want to unmap the buffers that contain the tail, and
+        ** all the buffers after it (since the tail must be at the
+        ** end of the file).  We don't want to unmap file data 
+        ** before the tail, since it might be dirty and waiting to 
+        ** reach disk
+        */
+        cur_index += bh->b_size ;
+        if (cur_index > tail_index) {
+          reiserfs_unmap_buffer(bh) ;
+        }
+	bh = next ;
+      } while (bh != head) ;
+    }
+  } 
+}
+
+/* this first locks inode (neither reads nor sync are permitted),
+   reads tail through page cache, insert direct item. When direct item
+   inserted successfully inode is left locked. Return value is always
+   what we expect from it (number of cut bytes). But when tail remains
+   in the unformatted node, we set mode to SKIP_BALANCING and unlock
+   inode */
+int indirect2direct (struct reiserfs_transaction_handle *th, 
+		     struct inode * p_s_inode,
+		     struct page *page, 
+		     struct path * p_s_path, /* path to the indirect item. */
+		     struct cpu_key * p_s_item_key, /* Key to look for unformatted node pointer to be cut. */
+		     loff_t n_new_file_size, /* New file size. */
+		     char * p_c_mode)
+{
+    struct super_block * p_s_sb = p_s_inode->i_sb;
+    struct item_head      s_ih;
+    unsigned long n_block_size = p_s_sb->s_blocksize;
+    char * tail;
+    int tail_len, round_tail_len;
+    loff_t pos, pos1; /* position of first byte of the tail */
+    struct cpu_key key;
+
+    p_s_sb->u.reiserfs_sb.s_indirect2direct ++;
+
+    *p_c_mode = M_SKIP_BALANCING;
+
+    /* store item head path points to. */
+    copy_item_head (&s_ih, PATH_PITEM_HEAD(p_s_path));
+
+    tail_len = (n_new_file_size & (n_block_size - 1));
+    if (!old_format_only (p_s_sb))
+	round_tail_len = ROUND_UP (tail_len);
+    else
+	round_tail_len = tail_len;
+
+    pos = le_ih_k_offset (&s_ih) - 1 + (le16_to_cpu (s_ih.ih_item_len) / UNFM_P_SIZE - 1) * p_s_sb->s_blocksize;
+    pos1 = pos;
+
+    // we are protected by i_sem. The tail can not disapper, not
+    // append can be done either
+    // we are in truncate or packing tail in file_release
+
+    tail = (char *)kmap(page) ; /* this can schedule */
+
+    if (path_changed (&s_ih, p_s_path)) {
+	/* re-search indirect item */
+	if ( search_for_position_by_key (p_s_sb, p_s_item_key, p_s_path) == POSITION_NOT_FOUND )
+	    reiserfs_panic(p_s_sb, "PAP-5520: indirect2direct: "
+			   "item to be converted %k does not exist", p_s_item_key);
+	copy_item_head(&s_ih, PATH_PITEM_HEAD(p_s_path));
+#ifdef CONFIG_REISERFS_CHECK
+	pos = le_ih_k_offset (&s_ih) - 1 + 
+	    (le16_to_cpu (s_ih.ih_item_len) / UNFM_P_SIZE - 1) * p_s_sb->s_blocksize;
+	if (pos != pos1)
+	    reiserfs_panic (p_s_sb, "vs-5530: indirect2direct: "
+			    "tail position changed while we were reading it");
+#endif
+    }
+
+
+    /* Set direct item header to insert. */
+    make_le_item_head (&s_ih, 0, inode_items_version (p_s_inode), pos1 + 1,
+		       TYPE_DIRECT, round_tail_len, 0xffff/*ih_free_space*/);
+
+    /* we want a pointer to the first byte of the tail in the page.
+    ** the page was locked and this part of the page was up to date when
+    ** indirect2direct was called, so we know the bytes are still valid
+    */
+    tail = tail + (pos & (PAGE_CACHE_SIZE - 1)) ;
+
+    PATH_LAST_POSITION(p_s_path)++;
+
+    key = *p_s_item_key;
+    set_cpu_key_k_type (&key, TYPE_DIRECT);
+    key.key_length = 4;
+    /* Insert tail as new direct item in the tree */
+    if ( reiserfs_insert_item(th, p_s_path, &key, &s_ih,
+			      tail ? tail : NULL) < 0 ) {
+	/* No disk memory. So we can not convert last unformatted node
+	   to the direct item.  In this case we used to adjust
+	   indirect items's ih_free_space. Now ih_free_space is not
+	   used, it would be ideal to write zeros to corresponding
+	   unformatted node. For now i_size is considered as guard for
+	   going out of file size */
+	kunmap(page) ;
+	return n_block_size - round_tail_len;
+    }
+    kunmap(page) ;
+
+    /* this will invalidate all the buffers in the page after
+    ** pos1
+    */
+    unmap_buffers(page, pos1) ;
+
+    // note: we have now the same as in above direct2indirect
+    // conversion: there are two keys which have matching first three
+    // key components. They only differ by the fouhth one.
+
+    /* We have inserted new direct item and must remove last
+       unformatted node. */
+    p_s_inode->i_blocks += (p_s_sb->s_blocksize / 512);
+    *p_c_mode = M_CUT;
+
+    /* we store position of first direct item in the in-core inode */
+    //mark_file_with_tail (p_s_inode, pos1 + 1);
+    p_s_inode->u.reiserfs_i.i_first_direct_byte = pos1 + 1;
+
+    return n_block_size - round_tail_len;
+}
+
+
+