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Date: Mon, 26 Jan 2015 23:37:18 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 16/54] e2fsck: decrement bad count _after_ remapping a
duplicate block
Decrement the bad count *after* we've shown that (a) we can allocate a
replacement block and (b) remap the file block. Unfortunately,
the only way to tell if the remapping succeeded is to wait until the
next clone_file_block() call or block_iterate3() returns.
Otherwise, there's a corruption error: we decrease the badcount once in
preparation to remap, then the remap fails (either we can't find a
replacement block or we have to split the extent tree and can't find a
new extent block), so we delete the file, which decreases the badcount
on the block a second time. Later on e2fsck will think that it's
straightened out all the duplicate blocks, which isn't true.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
e2fsck/pass1b.c | 32 +++++++++++++++++++++++++---
tests/f_cloneblock_alloc_error/expect.1 | 36 +++++++++++++++++++++++++++++++
tests/f_cloneblock_alloc_error/expect.2 | 7 ++++++
tests/f_cloneblock_alloc_error/image.gz | Bin
tests/f_cloneblock_alloc_error/name | 1 +
5 files changed, 73 insertions(+), 3 deletions(-)
create mode 100644 tests/f_cloneblock_alloc_error/expect.1
create mode 100644 tests/f_cloneblock_alloc_error/expect.2
create mode 100644 tests/f_cloneblock_alloc_error/image.gz
create mode 100644 tests/f_cloneblock_alloc_error/name
diff --git a/e2fsck/pass1b.c b/e2fsck/pass1b.c
index 2d1b448..cd967f4 100644
--- a/e2fsck/pass1b.c
+++ b/e2fsck/pass1b.c
@@ -725,8 +725,30 @@ struct clone_struct {
char *buf;
e2fsck_t ctx;
struct ext2_inode *inode;
+
+ struct dup_cluster *save_dup_cluster;
+ blk64_t save_blocknr;
};
+/*
+ * Decrement the bad count *after* we've shown that (a) we can allocate a
+ * replacement block and (b) remap the file blocks. Unfortunately, there's no
+ * way to find out if the remap succeeded until either the next
+ * clone_file_block() call (an error when remapping the block after returning
+ * BLOCK_CHANGED will halt the iteration) or after block_iterate() returns.
+ * Otherwise, it's possible that we decrease the badcount once in preparation
+ * to remap, then the remap fails (either we can't find a replacement block or
+ * we have to split the extent tree and can't find a new extent block), so we
+ * delete the file, which decreases the badcount again.
+ */
+static void deferred_dec_badcount(struct clone_struct *cs)
+{
+ if (!cs->save_dup_cluster)
+ return;
+ decrement_badcount(cs->ctx, cs->save_blocknr, cs->save_dup_cluster);
+ cs->save_dup_cluster = NULL;
+}
+
static int clone_file_block(ext2_filsys fs,
blk64_t *block_nr,
e2_blkcnt_t blockcnt,
@@ -734,7 +756,7 @@ static int clone_file_block(ext2_filsys fs,
int ref_offset EXT2FS_ATTR((unused)),
void *priv_data)
{
- struct dup_cluster *p;
+ struct dup_cluster *p = NULL;
blk64_t new_block;
errcode_t retval;
struct clone_struct *cs = (struct clone_struct *) priv_data;
@@ -744,6 +766,7 @@ static int clone_file_block(ext2_filsys fs,
int is_meta = 0;
ctx = cs->ctx;
+ deferred_dec_badcount(cs);
if (HOLE_BLKADDR(*block_nr))
return 0;
@@ -768,8 +791,6 @@ static int clone_file_block(ext2_filsys fs,
}
p = (struct dup_cluster *) dnode_get(n);
- if (!is_meta)
- decrement_badcount(ctx, *block_nr, p);
cs->dup_cluster = c;
/*
@@ -819,6 +840,8 @@ cluster_alloc_ok:
cs->errcode = retval;
return BLOCK_ABORT;
}
+ cs->save_dup_cluster = (is_meta ? NULL : p);
+ cs->save_blocknr = *block_nr;
*block_nr = new_block;
ext2fs_mark_block_bitmap2(ctx->block_found_map, new_block);
ext2fs_mark_block_bitmap2(fs->block_map, new_block);
@@ -848,6 +871,8 @@ static errcode_t clone_file(e2fsck_t ctx, ext2_ino_t ino,
cs.ctx = ctx;
cs.ino = ino;
cs.inode = &dp->inode;
+ cs.save_dup_cluster = NULL;
+ cs.save_blocknr = 0;
retval = ext2fs_get_mem(fs->blocksize, &cs.buf);
if (retval)
return retval;
@@ -860,6 +885,7 @@ static errcode_t clone_file(e2fsck_t ctx, ext2_ino_t ino,
if (ext2fs_inode_has_valid_blocks2(fs, &dp->inode))
pctx.errcode = ext2fs_block_iterate3(fs, ino, 0, block_buf,
clone_file_block, &cs);
+ deferred_dec_badcount(&cs);
ext2fs_mark_bb_dirty(fs);
if (pctx.errcode) {
fix_problem(ctx, PR_1B_BLOCK_ITERATE, &pctx);
diff --git a/tests/f_cloneblock_alloc_error/expect.1 b/tests/f_cloneblock_alloc_error/expect.1
new file mode 100644
index 0000000..24fe1ff
--- /dev/null
+++ b/tests/f_cloneblock_alloc_error/expect.1
@@ -0,0 +1,36 @@
+Pass 1: Checking inodes, blocks, and sizes
+Inode 12, i_size is 0, should be 2015232. Fix? yes
+
+
+Running additional passes to resolve blocks claimed by more than one inode...
+Pass 1B: Rescanning for multiply-claimed blocks
+Multiply-claimed block(s) in inode 13: 8
+Multiply-claimed block(s) in inode 14: 8
+Pass 1C: Scanning directories for inodes with multiply-claimed blocks
+Pass 1D: Reconciling multiply-claimed blocks
+(There are 2 inodes containing multiply-claimed blocks.)
+
+File /b (inode #13, mod time Wed Jan 21 03:41:55 2015)
+ has 1 multiply-claimed block(s), shared with 1 file(s):
+ /c (inode #14, mod time Wed Jan 21 03:42:37 2015)
+Clone multiply-claimed blocks? yes
+
+clone_file: Could not allocate block in ext2 filesystem returned from clone_file_block
+Couldn't clone file: Could not allocate block in ext2 filesystem
+Delete file? yes
+
+File /c (inode #14, mod time Wed Jan 21 03:42:37 2015)
+ has 1 multiply-claimed block(s), shared with 1 file(s):
+ /b (inode #13, mod time Wed Jan 21 03:41:55 2015)
+Multiply-claimed blocks already reassigned or cloned.
+
+Pass 2: Checking directory structure
+Entry 'b' in / (2) has deleted/unused inode 13. Clear? yes
+
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 13/128 files (7.7% non-contiguous), 512/512 blocks
+Exit status is 1
diff --git a/tests/f_cloneblock_alloc_error/expect.2 b/tests/f_cloneblock_alloc_error/expect.2
new file mode 100644
index 0000000..f7781ec
--- /dev/null
+++ b/tests/f_cloneblock_alloc_error/expect.2
@@ -0,0 +1,7 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+test_filesys: 13/128 files (7.7% non-contiguous), 512/512 blocks
+Exit status is 0
diff --git a/tests/f_cloneblock_alloc_error/image.gz b/tests/f_cloneblock_alloc_error/image.gz
new file mode 100644
index 0000000000000000000000000000000000000000..ed01df1b9fb7a10f49338cd994ca4ef4cf646bba
GIT binary patch
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diff --git a/tests/f_cloneblock_alloc_error/name b/tests/f_cloneblock_alloc_error/name
new file mode 100644
index 0000000..9196e89
--- /dev/null
+++ b/tests/f_cloneblock_alloc_error/name
@@ -0,0 +1 @@
+decrement badcount after remapping duplicate block
--
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