db: increase metadump's default overly long extent discard threshold

Back in 88b8e1d6d7 ("Make xfs_metadump more robust against bad data"), metadump grew the ability to ignore a directory extent if it was longer than 20 blocks. Presumably this was to protect metadump from dumping absurdly long extents resulting from bmbt corruption, but it's certainly possible to create a directory with an extent longer than 20 blocks. Hilariously, the discards happen with no warning unless the caller explicitly set -w.

This was raised to 1000 blocks in 7431d134fe8 ("Increase default maximum extent size for xfs_metadump when copying..."), but it's still possible to create a directory with an extent longer than 1000 blocks.

Increase the threshold to MAXEXTLEN blocks because it's totally valid for the filesystem to create extents up to that length.

Signed-off-by Darrick J. Wong <[email protected]>

---
v2: update manpage

---
 db/metadump.c           |    2 +-
 man/man8/xfs_metadump.8 |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

db/metadump.c +1 -1

index 6dd06c3..8ffb90f 100644
@@ -32,7 +32,7 @@
 #include "field.h"
 #include "dir2.h"
 
-#define DEFAULT_MAX_EXT_SIZE	1000
+#define DEFAULT_MAX_EXT_SIZE	MAXEXTLEN
 
 /*
  * It's possible that multiple files in a directory (or attributes

man/man8/xfs_metadump.8 +1 -2

index 3731d6a..b6af4b6 100644
@@ -114,7 +114,7 @@ copied.
 .B \-m
 Set the maximum size of an allowed metadata extent.  Extremely large metadata
 extents are likely to be corrupt, and will be skipped if they exceed
-this value.  The default size is 1000 blocks.
+this value.  The default size is 2097151 blocks.
 .TP
 .B \-o
 Disables obfuscation of file names and extended attributes.
--

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