Lest Ted think I'm completely ignoring this.. ;)
This version can remap or unmap the first or last block in
an extent, and can map an unmapped block.
* TODO:
* Handle remapping block in middle of extent (requires splitting node)
* Handle case where parent is full (requires splitting parent)
I still have to make the split function recurse up to the root, as well.
-Eric
Index: e2fsprogs/lib/ext2fs/extent.c
===================================================================
--- e2fsprogs.orig/lib/ext2fs/extent.c 2008-04-29 16:47:09.609482537 -0500
+++ e2fsprogs/lib/ext2fs/extent.c 2008-05-06 16:48:05.453775768 -0500
@@ -628,6 +628,64 @@ errcode_t ext2fs_extent_goto(ext2_extent
return extent_goto(handle, 0, blk);
}
+/*
+ * Traverse back up to root fixing parents of current node as needed.
+ *
+ * If we changed start of first entry in a node, fix parent index start
+ * and so on.
+ *
+ * Safe to call for any position in node; if not at the first entry,
+ * will simply return.
+ */
+errcode_t ext2fs_extent_fix_parents(ext2_extent_handle_t handle)
+{
+ int retval = 0;
+ blk64_t start;
+ struct extent_path *path;
+ struct ext2fs_extent extent;
+
+ EXT2_CHECK_MAGIC(handle, EXT2_ET_MAGIC_EXTENT_HANDLE);
+
+ if (!(handle->fs->flags & EXT2_FLAG_RW))
+ return EXT2_ET_RO_FILSYS;
+
+ if (!handle->path)
+ return EXT2_ET_NO_CURRENT_NODE;
+
+ path = handle->path + handle->level;
+ if (!path->curr)
+ return EXT2_ET_NO_CURRENT_NODE;
+
+ retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
+ if (retval)
+ goto done;
+
+ /* modified node's start block */
+ start = extent.e_lblk;
+
+ /* traverse up until index not first, or startblk matches, or top */
+ while (handle->level > 0 &&
+ (path->left == path->entries - 1)) {
+ retval = ext2fs_extent_get(handle, EXT2_EXTENT_UP, &extent);
+ if (retval)
+ goto done;
+ if (extent.e_lblk == start)
+ break;
+ path = handle->path + handle->level;
+ extent.e_len += (extent.e_lblk - start);
+ extent.e_lblk = start;
+ retval = ext2fs_extent_replace(handle, 0, &extent);
+ if (retval)
+ goto done;
+ update_path(handle);
+ }
+
+ /* put handle back to where we started */
+ retval = ext2fs_extent_goto(handle, start);
+done:
+ return retval;
+}
+
errcode_t ext2fs_extent_replace(ext2_extent_handle_t handle,
int flags EXT2FS_ATTR((unused)),
struct ext2fs_extent *extent)
@@ -859,6 +917,161 @@ done:
return retval;
}
+/*
+ * Sets the physical block for a logical file block in the extent tree.
+ *
+ * May: map unmapped, unmap mapped, or remap mapped blocks.
+ *
+ * Mapping an unmapped block adds a single-block extent.
+ *
+ * Unmapping first or last block modifies extent in-place
+ * - But may need to fix parent's starts too in first-block case
+ *
+ * Mapping any unmapped block requires adding a (single-block) extent
+ * and inserting into proper point in tree.
+ *
+ * Modifying (unmapping or remapping) a block in the middle
+ * of an extent requires splitting the extent.
+ * - Remapping case requres new single-block extent.
+ *
+ * Remapping first or last block adds an extent
+ *
+ * We really need extent adding to be smart about merging.
+ *
+ * TODO:
+ * Handle remapping block in middle of extent (requires splitting node)
+ * Handle case where parent is full (requires splitting parent)
+ */
+
+/* NB: if unmapping or mapping an unmapped block, does not change i_count */
+errcode_t ext2fs_extent_set_bmap(ext2_extent_handle_t handle,
+ blk64_t logical, blk64_t physical)
+{
+ int retval = 0;
+ int mapped = 1; /* logical is mapped? */
+ struct extent_path *path;
+ struct ext2fs_extent extent;
+ struct ext2fs_extent newextent;
+
+ EXT2_CHECK_MAGIC(handle, EXT2_ET_MAGIC_EXTENT_HANDLE);
+
+ if (!(handle->fs->flags & EXT2_FLAG_RW))
+ return EXT2_ET_RO_FILSYS;
+
+ /* go to the logical spot we want to (re/un)map */
+ retval = ext2fs_extent_goto(handle, logical);
+ if (retval) {
+ if (retval == EXT2_ET_EXTENT_NOT_FOUND) {
+ retval = 0;
+ mapped = 0;
+ if (!physical) {
+ dbg_printf("block already unmapped\n");
+ goto done;
+ }
+ } else
+ goto done;
+ }
+
+ if (!handle->path)
+ return EXT2_ET_NO_CURRENT_NODE;
+
+ path = handle->path + handle->level;
+ if (!path->curr)
+ return EXT2_ET_NO_CURRENT_NODE;
+
+ /*
+ * This may be the extent *before* the requested logical,
+ * if it's currently unmapped.
+ */
+ retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
+ if (retval)
+ goto done;
+
+ /* check if already pointing to the requested physical */
+ if (mapped && extent.e_pblk + (logical - extent.e_lblk) == physical) {
+ dbg_printf("physical block unchanged\n");
+ goto done;
+ }
+
+ /* if (re)mapping, set up new extent, we'll insert it later */
+ if (physical) {
+ newextent.e_len = 1;
+ newextent.e_pblk = physical;
+ newextent.e_lblk = logical;
+ newextent.e_flags = EXT2_EXTENT_FLAGS_LEAF;
+ }
+
+ if (!mapped) {
+ dbg_printf("mapping unmapped logical block\n");
+ retval = ext2fs_extent_insert(handle,
+ EXT2_EXTENT_INSERT_AFTER, &newextent);
+ if (retval)
+ goto done;
+ retval = ext2fs_extent_fix_parents(handle);
+ if (retval)
+ goto done;
+ } else if (logical == extent.e_lblk + extent.e_len - 1 &&
+ extent.e_len == 1) {
+ dbg_printf("(re/un)mapping only block in extent\n");
+ if (physical) {
+ extent.e_pblk = physical;
+ retval = ext2fs_extent_replace(handle, 0, &extent);
+ } else {
+ retval = ext2fs_extent_delete(handle, 0);
+ if (retval)
+ goto done;
+ retval = ext2fs_extent_fix_parents(handle);
+ }
+
+ if (retval)
+ goto done;
+ } else if (logical == extent.e_lblk + extent.e_len - 1) {
+ dbg_printf("(re/un)mapping last block in extent\n");
+ extent.e_len--;
+ retval = ext2fs_extent_replace(handle, 0, &extent);
+ if (retval)
+ goto done;
+ if (physical) {
+ retval = ext2fs_extent_insert(handle,
+ EXT2_EXTENT_INSERT_AFTER, &newextent);
+ if (retval)
+ goto done;
+ } else {
+ printf("fixing parents\n");
+ retval = ext2fs_extent_fix_parents(handle);
+ if (retval)
+ goto done;
+ }
+ } else if (logical == extent.e_lblk) {
+ dbg_printf("(re/un)mapping first block in extent\n");
+ extent.e_pblk++;
+ extent.e_lblk++;
+ extent.e_len--;
+ retval = ext2fs_extent_replace(handle, 0, &extent);
+ if (retval)
+ goto done;
+ if (physical) {
+ /* insert new extent ahead of current */
+ retval = ext2fs_extent_insert(handle,
+ 0, &newextent);
+ if (retval)
+ goto done;
+ } else {
+ retval = ext2fs_extent_fix_parents(handle);
+ if (retval)
+ goto done;
+ }
+ } else {
+ dbg_printf("(re/un)mapping in middle of extent\n");
+ /* need to split this extent; later */
+ retval = EXT2_ET_OP_NOT_SUPPORTED;
+ goto done;
+ }
+
+done:
+ return retval;
+}
+
errcode_t ext2fs_extent_delete(ext2_extent_handle_t handle,
int flags EXT2FS_ATTR((unused)))
{
@@ -1163,7 +1376,7 @@ void do_insert_node(int argc, char *argv
}
if (argc != 4) {
- fprintf(stderr, "usage: %s <lblk> <len> <pblk>\n", cmd);
+ fprintf(stderr, "usage: %s [--after] <lblk> <len> <pblk>\n", cmd);
return;
}
@@ -1190,6 +1403,42 @@ void do_insert_node(int argc, char *argv
do_current_node(argc, argv);
}
+void do_set_bmap(int argc, char **argv)
+{
+ errcode_t retval;
+ blk_t logical;
+ blk_t physical;
+ char *cmd;
+ int err;
+
+ if (check_fs_read_write(argv[0]))
+ return;
+
+ cmd = argv[0];
+
+ if (argc != 3) {
+ fprintf(stderr, "usage: %s <lblk> <pblk>\n", cmd);
+ return;
+ }
+
+ logical = parse_ulong(argv[1], cmd,
+ "logical block", &err);
+ if (err)
+ return;
+
+ physical = parse_ulong(argv[2], cmd,
+ "physical block", &err);
+ if (err)
+ return;
+
+ retval = ext2fs_extent_set_bmap(current_handle, logical, (blk64_t) physical);
+ if (retval) {
+ com_err(cmd, retval, 0);
+ return;
+ }
+ do_current_node(argc, argv);
+}
+
void do_print_all(int argc, char **argv)
{
struct ext2fs_extent extent;
Index: e2fsprogs/lib/ext2fs/extent_dbg.ct
===================================================================
--- e2fsprogs.orig/lib/ext2fs/extent_dbg.ct 2008-04-29 16:39:13.204659932 -0500
+++ e2fsprogs/lib/ext2fs/extent_dbg.ct 2008-05-05 14:37:52.801892887 -0500
@@ -55,6 +55,9 @@ request do_insert_node, "Insert node",
request do_split_node, "Split node",
split_node, split;
+request do_set_bmap, "Set block mapping",
+ set_bmap;
+
request do_replace_node, "Insert node",
replace_node, replace;
--
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