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Date: Thu, 12 Nov 2009 01:01:58 -0500
From: Nick Dokos <nicholas.dokos@...com>
To: Theodore Ts'o <tytso@....edu>
Cc: nicholas.dokos@...com, linux-ext4@...r.kernel.org
Subject: [PATCH v2][64-bit e2fsprogs] 64-bit block number truncated in e2sck
pass2.
The first version of this patch (see
http://marc.info/?l=linux-ext4&m=125682539524168&w=2) dealt with the
problem of a directory whose blocks were beyond the 32-bit
boundary. e2fsck was truncating the block number in pass 2 and
generating spurious errors. The fix was to replace a call to
ext2fs_read_dir_block() by the corresponding 64-bit safe call to
ext2fs_read_dir_block3().
However, there is another call to ext2fs_read_dir_block() in
pass 1, specifically in the routine check_is_really_dir(),
a routine with a question mark over its head. Andreas Dilger
recommended that the routine should stay, so I've gone ahead
and fixed it up to deal with extent-mapped inodes as well.
I also added some comments reflecting my (possibly faulty)
understanding of what the routine is trying to do, so I'd
appreciate comments/corrections. In particular, I don't
quite understand why the relevant index for deciding whether
something can or cannot be a device file is 4, so I've left
it unchanged.
I'll follow up with another email that contains a couple
of test cases.
Thanks,
Nick
>From 44de200d84379ed6debb1bf054de57a8828a9e0d Mon Sep 17 00:00:00 2001
From: Nick Dokos <nicholas.dokos@...com>
Date: Wed, 11 Nov 2009 21:21:36 -0500
Subject: [PATCH] Deal with 64-bit block numbers in directory.
e2fsck was truncating the (> 2^32) block number of a directory in pass 2
and generating spurious errors. The fix is to replace a call to
ext2fs_read_dir_block() by the corresponding 64-bit safe call to
ext2fs_read_dir_block3().
The pass1 check_is_really_dir() function (which uses the above function,
and therefore needs the same fix) needs additional changes to deal with
extent-mapped inodes.
Signed-off-by: Nick Dokos <nicholas.dokos@...com>
---
e2fsck/pass1.c | 61 +++++++++++++++++++++++++++++++++++++++++++++-----------
e2fsck/pass2.c | 2 +-
2 files changed, 50 insertions(+), 13 deletions(-)
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 557d642..fcae923 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -405,34 +405,71 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
errcode_t retval;
blk64_t blk;
unsigned int i, rec_len, not_device = 0;
+ int extent_fs;
+ /* If the mode looks OK, we believe it. If the first block in
+ * the i_block array is 0, this cannot be a directory. If the
+ * inode is extent-mapped, it is still the case that the latter
+ * cannot be 0 - the magic number in the extent header would make
+ * it nonzero.
+ */
if (LINUX_S_ISDIR(inode->i_mode) || LINUX_S_ISREG(inode->i_mode) ||
LINUX_S_ISLNK(inode->i_mode) || inode->i_block[0] == 0)
return;
- for (i=0; i < EXT2_N_BLOCKS; i++) {
- blk = inode->i_block[i];
- if (!blk)
- continue;
- if (i >= 4)
- not_device++;
+ /* Check the block numbers in the i_block array for validity:
+ * zero blocks are skipped (but the first one cannot be zero - see above),
+ * other blocks are checked against the first and max data blocks (from the
+ * the superblock) and against the block bitmap. Any invalid block found
+ * means this cannot be a directory.
+ *
+ * If there are non-zero blocks past the fourth entry, then this cannot be
+ * a device file: we remember that for the next check.
+ *
+ * For extent mapped files, we don't do any sanity checking: just try to
+ * get the phys block of logical block 0 and run with it.
+ */
+ extent_fs = (ctx->fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_EXTENTS);
+ if (extent_fs && (inode->i_flags & EXT4_EXTENTS_FL)) {
+ /* extent mapped */
+ if (ext2fs_bmap2(ctx->fs, pctx->ino, inode, 0, 0, 0, 0, &blk))
+ return;
+ /* device files are never extent mapped */
+ not_device++;
+ } else {
+ for (i=0; i < EXT2_N_BLOCKS; i++) {
+ blk = inode->i_block[i];
+ if (!blk)
+ continue;
+ if (i >= 4)
+ not_device++;
- if (blk < ctx->fs->super->s_first_data_block ||
- blk >= ext2fs_blocks_count(ctx->fs->super) ||
- ext2fs_fast_test_block_bitmap2(ctx->block_found_map, blk))
- return; /* Invalid block, can't be dir */
+ if (blk < ctx->fs->super->s_first_data_block ||
+ blk >= ext2fs_blocks_count(ctx->fs->super) ||
+ ext2fs_fast_test_block_bitmap2(ctx->block_found_map, blk))
+ return; /* Invalid block, can't be dir */
+ }
+ blk = (blk64_t) inode->i_block[0];
}
+ /* If the mode says this is a device file and the i_links_count field
+ * is sane and we have not ruled it out as a device file previously,
+ * we declare it a device file, not a directory.
+ */
if ((LINUX_S_ISCHR(inode->i_mode) || LINUX_S_ISBLK(inode->i_mode)) &&
(inode->i_links_count == 1) && !not_device)
return;
+ /* read the first block */
old_op = ehandler_operation(_("reading directory block"));
- retval = ext2fs_read_dir_block(ctx->fs, inode->i_block[0], buf);
+ retval = ext2fs_read_dir_block3(ctx->fs, blk, buf, ctx->fs->flags);
ehandler_operation(0);
if (retval)
return;
+ /* the rest is independent of whether this is block-mapped or
+ * extent-mapped, so it can remain untouched.
+ */
dirent = (struct ext2_dir_entry *) buf;
retval = ext2fs_get_rec_len(ctx->fs, dirent, &rec_len);
if (retval)
diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
index b757131..7b75f83 100644
--- a/e2fsck/pass2.c
+++ b/e2fsck/pass2.c
@@ -780,7 +780,7 @@ static int check_dir_block(ext2_filsys fs,
#endif
old_op = ehandler_operation(_("reading directory block"));
- cd->pctx.errcode = ext2fs_read_dir_block(fs, block_nr, buf);
+ cd->pctx.errcode = ext2fs_read_dir_block3(fs, block_nr, buf, fs->flags);
ehandler_operation(0);
if (cd->pctx.errcode == EXT2_ET_DIR_CORRUPTED)
cd->pctx.errcode = 0; /* We'll handle this ourselves */
--
1.6.0.6
--
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