Decrease stack usage in JFS.

	We have only 92K of stack and using over 4K per frame is wasteful

	* grub-core/fs/jfs.c (getblk): Allocate on heap rather than on
	stack. Note: this function is recursive.
	(grub_jfs_read_inode): Read only part we care about.

diff --git a/ChangeLog b/ChangeLog
index c86a2749e77dc71ddc3c86f825f1e8cfdb7260b2..3022acf6e89d9ed81585c24c4bbd650f1d73c847 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,18 @@
+2013-11-16  Vladimir Serbinenko  <phcoder@gmail.com>
+
+       Decrease stack usage in JFS.
+
+       We have only 92K of stack and using over 4K per frame is wasteful
+
+       * grub-core/fs/jfs.c (getblk): Allocate on heap rather than on
+       stack. Note: this function is recursive.
+       (grub_jfs_read_inode): Read only part we care about.
+
 2013-11-16  Leif Lindholm <leif.lindholm@linaro.org>
 
        * grub-core/kern/arm/uboot/startup.S: fix grub_uboot_syscall va_arg
        handling
+
 2013-11-16  Andrey Borzenkov <arvidjaar@gmail.com>
 
        * configure.ac: Restore -nostdlib for libgcc symbols tests.

diff --git a/grub-core/fs/jfs.c b/grub-core/fs/jfs.c
index 06250149221a4a79a4ade3634fc0d8c03fa64d65..3251baa6e8f12ab4cbbe8f802786609391c91f7f 100644 (file)
--- a/grub-core/fs/jfs.c
+++ b/grub-core/fs/jfs.c
@@ -72,10 +72,13 @@ struct grub_jfs_extent
   grub_uint32_t blk2;
 } __attribute__ ((packed));
 
+#define GRUB_JFS_IAG_INODES_OFFSET 3072
+#define GRUB_JFS_IAG_INODES_COUNT 128
+
 struct grub_jfs_iag
 {
-  grub_uint8_t unused[3072];
-  struct grub_jfs_extent inodes[128];
+  grub_uint8_t unused[GRUB_JFS_IAG_INODES_OFFSET];
+  struct grub_jfs_extent inodes[GRUB_JFS_IAG_INODES_COUNT];
 } __attribute__ ((packed));
 
 
@@ -283,20 +286,25 @@ getblk (struct grub_jfs_treehead *treehead,
 
   if (found != -1)
     {
+      grub_int64_t ret = -1;
       struct
       {
        struct grub_jfs_treehead treehead;
        struct grub_jfs_tree_extent extents[254];
-      } tree;
+      } *tree;
 
-      if (grub_disk_read (data->disk,
-                         ((grub_disk_addr_t) grub_le_to_cpu32 (extents[found].extent.blk2))
-                         << (grub_le_to_cpu16 (data->sblock.log2_blksz)
-                             - GRUB_DISK_SECTOR_BITS), 0,
-                         sizeof (tree), (char *) &tree))
+      tree = grub_zalloc (sizeof (*tree));
+      if (!tree)
        return -1;
 
-      return getblk (&tree.treehead, &tree.extents[0], data, blk);
+      if (!grub_disk_read (data->disk,
+                          ((grub_disk_addr_t) grub_le_to_cpu32 (extents[found].extent.blk2))
+                          << (grub_le_to_cpu16 (data->sblock.log2_blksz)
+                              - GRUB_DISK_SECTOR_BITS), 0,
+                          sizeof (*tree), (char *) tree))
+       ret = getblk (&tree->treehead, &tree->extents[0], data, blk);
+      grub_free (tree);
+      return ret;
     }
 
   return -1;
@@ -316,7 +324,7 @@ static grub_err_t
 grub_jfs_read_inode (struct grub_jfs_data *data, grub_uint32_t ino,
                     struct grub_jfs_inode *inode)
 {
-  struct grub_jfs_iag iag;
+  struct grub_jfs_extent iag_inodes[GRUB_JFS_IAG_INODES_COUNT];
   grub_uint32_t iagnum = ino / 4096;
   unsigned inoext = (ino % 4096) / 32;
   unsigned inonum = (ino % 4096) % 32;
@@ -330,11 +338,12 @@ grub_jfs_read_inode (struct grub_jfs_data *data, grub_uint32_t ino,
   /* Read in the IAG.  */
   if (grub_disk_read (data->disk,
                      iagblk << (grub_le_to_cpu16 (data->sblock.log2_blksz)
-                                - GRUB_DISK_SECTOR_BITS), 0,
-                     sizeof (struct grub_jfs_iag), &iag))
+                                - GRUB_DISK_SECTOR_BITS),
+                     GRUB_JFS_IAG_INODES_OFFSET,
+                     sizeof (iag_inodes), &iag_inodes))
     return grub_errno;
 
-  inoblk = grub_le_to_cpu32 (iag.inodes[inoext].blk2);
+  inoblk = grub_le_to_cpu32 (iag_inodes[inoext].blk2);
   inoblk <<= (grub_le_to_cpu16 (data->sblock.log2_blksz)
              - GRUB_DISK_SECTOR_BITS);
   inoblk += inonum;