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Subject[63/90] ext4: make sure directory and symlink blocks are revoked
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
(cherry picked from commit 50689696867d95b38d9c7be640a311494a04fb86)

When an inode gets unlinked, the functions ext4_clear_blocks() and
ext4_remove_blocks() call ext4_forget() for all the buffer heads
corresponding to the deleted inode's data blocks. If the inode is a
directory or a symlink, the is_metadata parameter must be non-zero so
ext4_forget() will revoke them via jbd2_journal_revoke(). Otherwise,
if these blocks are reused for a data file, and the system crashes
before a journal checkpoint, the journal replay could end up
corrupting these data blocks.

Thanks to Curt Wohlgemuth for pointing out potential problems in this
area.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/ext4/extents.c | 2 +-
fs/ext4/inode.c | 6 ++++--
2 files changed, 5 insertions(+), 3 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2055,7 +2055,7 @@ static int ext4_remove_blocks(handle_t *
ext_debug("free last %u blocks starting %llu\n", num, start);
for (i = 0; i < num; i++) {
bh = sb_find_get_block(inode->i_sb, start + i);
- ext4_forget(handle, 0, inode, bh, start + i);
+ ext4_forget(handle, metadata, inode, bh, start + i);
}
ext4_free_blocks(handle, inode, start, num, metadata);
} else if (from == le32_to_cpu(ex->ee_block)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4110,6 +4110,8 @@ static void ext4_clear_blocks(handle_t *
__le32 *last)
{
__le32 *p;
+ int is_metadata = S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode);
+
if (try_to_extend_transaction(handle, inode)) {
if (bh) {
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
@@ -4140,11 +4142,11 @@ static void ext4_clear_blocks(handle_t *

*p = 0;
tbh = sb_find_get_block(inode->i_sb, nr);
- ext4_forget(handle, 0, inode, tbh, nr);
+ ext4_forget(handle, is_metadata, inode, tbh, nr);
}
}

- ext4_free_blocks(handle, inode, block_to_free, count, 0);
+ ext4_free_blocks(handle, inode, block_to_free, count, is_metadata);
}

/**



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