Re: xfs_repair segfaults with ag_stride option

Christoph Hellwig
2012-02-02T12:42:53Z

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Hi Tom,

On Wed, Feb 01, 2012 at 01:36:12PM +0000, Tom Crane wrote:
> Dear XFS Support,
> I am attempting to use xfs_repair to fix a damaged FS but always
> get a segfault if and only if -o ag_stride is specified. I have
> tried ag_stride=2,8,16 & 32. The FS is approx 60T. I can't find
> reports of this particular problem on the mailing list archive.
> Further details are;
>
> xfs_repair version 3.1.7, recently downloaded via git repository.
> uname -a
> Linux store3 2.6.18-274.17.1.el5 #1 SMP Wed Jan 11 11:10:32 CET 2012
> x86_64 x86_64 x86_64 GNU/Linux

Thanks for the detailed bug report.

Can you please try the attached patch?

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From: Christoph Hellwig <hch@lst.de>
Subject: repair: fix incorrect use of thread local data in dir and attr code

The attribute and dirv1 code use pthread thread local data incorrectly in
a few places, which will make them fail in horrible ways when using the
ag_stride options.

Replace the use of thread local data with simple local allocations given
that there is no needed to micro-optimize these allocations as much
as e.g. the extent map. The added benefit is that we have to allocate
less memory, and can free it quickly.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: xfsprogs-dev/repair/attr_repair.c
===================================================================
--- xfsprogs-dev.orig/repair/attr_repair.c 2012-02-02 09:25:50.000000000 +0000
+++ xfsprogs-dev/repair/attr_repair.c 2012-02-02 11:14:06.000000000 +0000
@@ -363,12 +363,6 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t in
return (clearit);
}

-/*
- * freespace map for directory and attribute leaf blocks (1 bit per byte)
- * 1 == used, 0 == free
- */
-size_t ts_attr_freemap_size = sizeof(da_freemap_t) * DA_BMAP_SIZE;
-
/* The block is read in. The magic number and forward / backward
* links are checked by the caller process_leaf_attr.
* If any problems occur the routine returns with non-zero. In
@@ -503,7 +497,7 @@ process_leaf_attr_block(
{
xfs_attr_leaf_entry_t *entry;
int i, start, stop, clearit, usedbs, firstb, thissize;
- da_freemap_t *attr_freemap = ts_attr_freemap();
+ da_freemap_t *attr_freemap;

clearit = usedbs = 0;
*repair = 0;
@@ -519,7 +513,7 @@ process_leaf_attr_block(
return (1);
}

- init_da_freemap(attr_freemap);
+ attr_freemap = alloc_da_freemap(mp);
(void) set_da_freemap(mp, attr_freemap, 0, stop);

/* go thru each entry checking for problems */
@@ -636,6 +630,8 @@ process_leaf_attr_block(
* we can add it then.
*/
}
+
+ free(attr_freemap);
return (clearit); /* and repair */
}

Index: xfsprogs-dev/repair/dir.c
===================================================================
--- xfsprogs-dev.orig/repair/dir.c 2012-02-02 09:25:50.000000000 +0000
+++ xfsprogs-dev/repair/dir.c 2012-02-02 11:17:20.000000000 +0000
@@ -495,23 +495,19 @@ process_shortform_dir(
}

/*
- * freespace map for directory leaf blocks (1 bit per byte)
- * 1 == used, 0 == free
+ * Allocate a freespace map for directory or attr leaf blocks (1 bit per byte)
+ * 1 == used, 0 == free.
*/
-size_t ts_dir_freemap_size = sizeof(da_freemap_t) * DA_BMAP_SIZE;
-
-void
-init_da_freemap(da_freemap_t *dir_freemap)
+da_freemap_t *
+alloc_da_freemap(struct xfs_mount *mp)
{
- memset(dir_freemap, 0, sizeof(da_freemap_t) * DA_BMAP_SIZE);
+ return calloc(1, mp->m_sb.sb_blocksize / NBBY);
}

/*
- * sets directory freemap, returns 1 if there is a conflict
- * returns 0 if everything's good. the range [start, stop) is set.
- * right now, we just use the static array since only one directory
- * block will be processed at once even though the interface allows
- * you to pass in arbitrary da_freemap_t array's.
+ * Set the he range [start, stop) in the directory freemap.
+ *
+ * Returns 1 if there is a conflict or 0 if everything's good.
*
* Within a char, the lowest bit of the char represents the byte with
* the smallest address
@@ -728,28 +724,6 @@ _("- derived hole (base %d, size %d) in
return(res);
}

-#if 0
-void
-test(xfs_mount_t *mp)
-{
- int i = 0;
- da_hole_map_t holemap;
-
- init_da_freemap(dir_freemap);
- memset(&holemap, 0, sizeof(da_hole_map_t));
-
- set_da_freemap(mp, dir_freemap, 0, 50);
- set_da_freemap(mp, dir_freemap, 100, 126);
- set_da_freemap(mp, dir_freemap, 126, 129);
- set_da_freemap(mp, dir_freemap, 130, 131);
- set_da_freemap(mp, dir_freemap, 150, 160);
- process_da_freemap(mp, dir_freemap, &holemap);
-
- return;
-}
-#endif
-
-
/*
* walk tree from root to the left-most leaf block reading in
* blocks and setting up cursor. passes back file block number of the
@@ -1366,8 +1340,6 @@ verify_da_path(xfs_mount_t *mp,
return(0);
}

-size_t ts_dirbuf_size = 64*1024;
-
/*
* called by both node dir and leaf dir processing routines
* validates all contents *but* the sibling pointers (forw/back)
@@ -1441,7 +1413,7 @@ process_leaf_dir_block(
char fname[MAXNAMELEN + 1];
da_hole_map_t holemap;
da_hole_map_t bholemap;
- unsigned char *dir_freemap = ts_dir_freemap();
+ da_freemap_t *dir_freemap;

#ifdef XR_DIR_TRACE
fprintf(stderr, "\tprocess_leaf_dir_block - ino %" PRIu64 "\n", ino);
@@ -1450,7 +1422,7 @@ process_leaf_dir_block(
/*
* clear static dir block freespace bitmap
*/
- init_da_freemap(dir_freemap);
+ dir_freemap = alloc_da_freemap(mp);

*buf_dirty = 0;
first_used = mp->m_sb.sb_blocksize;
@@ -1462,7 +1434,8 @@ process_leaf_dir_block(
do_warn(
_("directory block header conflicts with used space in directory inode %" PRIu64 "\n"),
ino);
- return(1);
+ res = 1;
+ goto out;
}

/*
@@ -1778,8 +1751,8 @@ _("entry references free inode %" PRIu64
do_warn(
_("bad size, entry #%d in dir inode %" PRIu64 ", block %u -- entry overflows block\n"),
i, ino, da_bno);
-
- return(1);
+ res = 1;
+ goto out;
}

start = (__psint_t)&leaf->entries[i] - (__psint_t)leaf;;
@@ -1789,7 +1762,8 @@ _("bad size, entry #%d in dir inode %" P
do_warn(
_("dir entry slot %d in block %u conflicts with used space in dir inode %" PRIu64 "\n"),
i, da_bno, ino);
- return(1);
+ res = 1;
+ goto out;
}

/*
@@ -2183,7 +2157,7 @@ _("- existing hole info for block %d, di
_("- compacting block %u in dir inode %" PRIu64 "\n"),
da_bno, ino);

- new_leaf = (xfs_dir_leafblock_t *) ts_dirbuf();
+ new_leaf = malloc(mp->m_sb.sb_blocksize);

/*
* copy leaf block header
@@ -2223,6 +2197,7 @@ _("- existing hole info for block %d, di
do_warn(
_("not enough space in block %u of dir inode %" PRIu64 " for all entries\n"),
da_bno, ino);
+ free(new_leaf);
break;
}

@@ -2284,6 +2259,7 @@ _("- existing hole info for block %d, di
* final step, copy block back
*/
memmove(leaf, new_leaf, mp->m_sb.sb_blocksize);
+ free(new_leaf);

*buf_dirty = 1;
} else {
@@ -2302,10 +2278,13 @@ _("- existing hole info for block %d, di
junk_zerolen_dir_leaf_entries(mp, leaf, ino, buf_dirty);
}
#endif
+
+out:
+ free(dir_freemap);
#ifdef XR_DIR_TRACE
fprintf(stderr, "process_leaf_dir_block returns %d\n", res);
#endif
- return((res > 0) ? 1 : 0);
+ return res > 0 ? 1 : 0;
}

/*
Index: xfsprogs-dev/repair/dir.h
===================================================================
--- xfsprogs-dev.orig/repair/dir.h 2012-02-02 09:28:58.000000000 +0000
+++ xfsprogs-dev/repair/dir.h 2012-02-02 11:09:41.000000000 +0000
@@ -21,9 +21,6 @@

struct blkmap;

-/* 1 bit per byte, max XFS blocksize == 64K bits / NBBY */
-#define DA_BMAP_SIZE 8192
-
typedef unsigned char da_freemap_t;

/*
@@ -81,9 +78,9 @@ get_first_dblock_fsbno(
xfs_ino_t ino,
xfs_dinode_t *dino);

-void
-init_da_freemap(
- da_freemap_t *dir_freemap);
+da_freemap_t *
+alloc_da_freemap(
+ xfs_mount_t *mp);

int
namecheck(
Index: xfsprogs-dev/repair/globals.h
===================================================================
--- xfsprogs-dev.orig/repair/globals.h 2012-02-02 09:33:29.000000000 +0000
+++ xfsprogs-dev/repair/globals.h 2012-02-02 09:34:49.000000000 +0000
@@ -185,10 +185,6 @@ EXTERN xfs_extlen_t sb_inoalignmt;
EXTERN __uint32_t sb_unit;
EXTERN __uint32_t sb_width;

-extern size_t ts_dirbuf_size;
-extern size_t ts_dir_freemap_size;
-extern size_t ts_attr_freemap_size;
-
EXTERN pthread_mutex_t *ag_locks;

EXTERN int report_interval;
Index: xfsprogs-dev/repair/init.c
===================================================================
--- xfsprogs-dev.orig/repair/init.c 2012-02-02 09:25:50.000000000 +0000
+++ xfsprogs-dev/repair/init.c 2012-02-02 09:37:02.000000000 +0000
@@ -29,67 +29,16 @@
#include "prefetch.h"
#include <sys/resource.h>

-/* TODO: dirbuf/freemap key usage is completely b0rked - only used for dirv1 */
-static pthread_key_t dirbuf_key;
-static pthread_key_t dir_freemap_key;
-static pthread_key_t attr_freemap_key;
-
extern pthread_key_t dblkmap_key;
extern pthread_key_t ablkmap_key;

static void
-ts_alloc(pthread_key_t key, unsigned n, size_t size)
-{
- void *voidp;
- voidp = calloc(n, size);
- if (voidp == NULL) {
- do_error(_("ts_alloc: cannot allocate thread specific storage\n"));
- /* NO RETURN */
- return;
- }
- pthread_setspecific(key, voidp);
-}
-
-static void
ts_create(void)
{
- /* create thread specific keys */
- pthread_key_create(&dirbuf_key, NULL);
- pthread_key_create(&dir_freemap_key, NULL);
- pthread_key_create(&attr_freemap_key, NULL);
-
pthread_key_create(&dblkmap_key, NULL);
pthread_key_create(&ablkmap_key, NULL);
}

-void
-ts_init(void)
-{
-
- /* allocate thread specific storage */
- ts_alloc(dirbuf_key, 1, ts_dirbuf_size);
- ts_alloc(dir_freemap_key, 1, ts_dir_freemap_size);
- ts_alloc(attr_freemap_key, 1, ts_attr_freemap_size);
-}
-
-void *
-ts_dirbuf(void)
-{
- return pthread_getspecific(dirbuf_key);
-}
-
-void *
-ts_dir_freemap(void)
-{
- return pthread_getspecific(dir_freemap_key);
-}
-
-void *
-ts_attr_freemap(void)
-{
- return pthread_getspecific(attr_freemap_key);
-}
-
static void
increase_rlimit(void)
{
@@ -156,7 +105,6 @@ xfs_init(libxfs_init_t *args)
do_error(_("couldn't initialize XFS library\n"));

ts_create();
- ts_init();
increase_rlimit();
pftrace_init();
}
Index: xfsprogs-dev/repair/protos.h
===================================================================
--- xfsprogs-dev.orig/repair/protos.h 2012-02-02 09:33:29.000000000 +0000
+++ xfsprogs-dev/repair/protos.h 2012-02-02 09:36:42.000000000 +0000
@@ -41,9 +41,5 @@ char *alloc_ag_buf(int size);
void print_inode_list(xfs_agnumber_t i);
char * err_string(int err_code);

-extern void *ts_attr_freemap(void);
-extern void *ts_dir_freemap(void);
-extern void *ts_dirbuf(void);
-extern void ts_init(void);
extern void thread_init(void);

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