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Date: Mon, 24 Mar 2008 17:13:42 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH e2fsprogs-next] Fix extent flag validity tests in pass1 on
big endian boxes.
Extent data is shared with the i_block[] space in the inode,
but it is always swapped on access, not when the inode is read.
In e2fsck/pass1.c we must be careful when checking validity
of the extents flag on the inode. If the flag was set when
the inode was read & swapped, then the extents data itself
(in ->i_block[]) was NOT swapped, so testing for a valid
extent header requires some swapping first. Then, if we
ultimately set the extents flag, all of i_block[] must be
re/un-swapped.
This passes the f_extent regression test on both ppc & x86.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
(I said I wanted to make it not-ugly... not sure I succeeded)
(also feel free to edit the comments if too verbose)
e2fsck/pass1.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++----
1 files changed, 48 insertions(+), 4 deletions(-)
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 79e9f23..0d6307d 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -680,7 +680,22 @@ void e2fsck_pass1(e2fsck_t ctx)
return;
}
}
-
+
+ /*
+ * Test for incorrect extent flag settings.
+ *
+ * On big-endian machines we must be careful:
+ * When the inode is read, the i_block array is not swapped
+ * if the extent flag is set. Therefore if we are testing
+ * for or fixing a wrongly-set flag, we must potentially
+ * (un)swap before testing, or after fixing.
+ */
+
+ /*
+ * In this case the extents flag was set when read, so
+ * extent_header_verify is ok. If the inode is cleared,
+ * no need to swap... so no extra swapping here.
+ */
if ((inode->i_flags & EXT4_EXTENTS_FL) && !extent_fs &&
(inode->i_links_count || (ino == EXT2_BAD_INO) ||
(ino == EXT2_ROOT_INO) || (ino == EXT2_JOURNAL_INO))) {
@@ -700,19 +716,48 @@ void e2fsck_pass1(e2fsck_t ctx)
}
}
+ /*
+ * For big-endian machines:
+ * If the inode didn't have the extents flag set when it
+ * was read, then the i_blocks array was swapped. To test
+ * as an extents header, we must swap it back first.
+ * IF we then set the extents flag, the entire i_block
+ * array must be un/re-swapped to make it proper extents data.
+ */
+
if (extent_fs && !(inode->i_flags & EXT4_EXTENTS_FL) &&
(inode->i_links_count || (ino == EXT2_BAD_INO) ||
(ino == EXT2_ROOT_INO) || (ino == EXT2_JOURNAL_INO)) &&
(LINUX_S_ISREG(inode->i_mode) ||
- LINUX_S_ISDIR(inode->i_mode)) &&
- (ext2fs_extent_header_verify(inode->i_block,
- sizeof(inode->i_block)) == 0)) {
+ LINUX_S_ISDIR(inode->i_mode))) {
+ void *ehp;
+#ifdef WORDS_BIGENDIAN
+ __u32 tmp_block[3];
+
+ for (i = 0; i < 3; i++)
+ tmp_block[i] = ext2fs_swab32(inode->i_block[i]);
+ ehp = tmp_block;
+#else
+ ehp = inode->i_block;
+#endif
+ if (ext2fs_extent_header_verify(ehp,
+ sizeof(inode->i_block)) == 0) {
if (fix_problem(ctx, PR_1_UNSET_EXTENT_FL, &pctx)) {
inode->i_flags |= EXT4_EXTENTS_FL;
+#ifdef WORDS_BIGENDIAN
+ for (i = 0; i < EXT2_N_BLOCKS; i++)
+ inode->i_block[i] =
+ ext2fs_swab32(inode->i_block[i]);
+#endif
e2fsck_write_inode(ctx, ino, inode, "pass1");
}
+ }
}
+ /*
+ * ext2fs_inode_has_valid_blocks does not actually look
+ * at i_block[] values, so not endian-sensitive here.
+ */
if (extent_fs && (inode->i_flags & EXT4_EXTENTS_FL) &&
LINUX_S_ISLNK(inode->i_mode) &&
!ext2fs_inode_has_valid_blocks(inode) &&
-- 1.5.4.1
--
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