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ocfs2: Add statistics for the checksum and ecc operations.
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It would be nice to know how often we get checksum failures.  Even
better, how many of them we can fix with the single bit ecc.  So, we add
a statistics structure.  The structure can be installed into debugfs
wherever the user wants.

For ocfs2, we'll put it in the superblock-specific debugfs directory and
pass it down from our higher-level functions.  The stats are only
registered with debugfs when the filesystem supports metadata ecc.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
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Joel Becker committed Jun 4, 2009
1 parent 15633a2 commit 73be192
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Showing 4 changed files with 240 additions and 19 deletions.
184 changes: 176 additions & 8 deletions fs/ocfs2/blockcheck.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,9 @@
#include <linux/crc32.h>
#include <linux/buffer_head.h>
#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <asm/byteorder.h>

#include <cluster/masklog.h>
Expand Down Expand Up @@ -222,6 +225,155 @@ void ocfs2_hamming_fix_block(void *data, unsigned int blocksize,
ocfs2_hamming_fix(data, blocksize * 8, 0, fix);
}


/*
* Debugfs handling.
*/

#ifdef CONFIG_DEBUG_FS

static int blockcheck_u64_get(void *data, u64 *val)
{
*val = *(u64 *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(blockcheck_fops, blockcheck_u64_get, NULL, "%llu\n");

static struct dentry *blockcheck_debugfs_create(const char *name,
struct dentry *parent,
u64 *value)
{
return debugfs_create_file(name, S_IFREG | S_IRUSR, parent, value,
&blockcheck_fops);
}

static void ocfs2_blockcheck_debug_remove(struct ocfs2_blockcheck_stats *stats)
{
if (stats) {
debugfs_remove(stats->b_debug_check);
stats->b_debug_check = NULL;
debugfs_remove(stats->b_debug_failure);
stats->b_debug_failure = NULL;
debugfs_remove(stats->b_debug_recover);
stats->b_debug_recover = NULL;
debugfs_remove(stats->b_debug_dir);
stats->b_debug_dir = NULL;
}
}

static int ocfs2_blockcheck_debug_install(struct ocfs2_blockcheck_stats *stats,
struct dentry *parent)
{
int rc = -EINVAL;

if (!stats)
goto out;

stats->b_debug_dir = debugfs_create_dir("blockcheck", parent);
if (!stats->b_debug_dir)
goto out;

stats->b_debug_check =
blockcheck_debugfs_create("blocks_checked",
stats->b_debug_dir,
&stats->b_check_count);

stats->b_debug_failure =
blockcheck_debugfs_create("checksums_failed",
stats->b_debug_dir,
&stats->b_failure_count);

stats->b_debug_recover =
blockcheck_debugfs_create("ecc_recoveries",
stats->b_debug_dir,
&stats->b_recover_count);
if (stats->b_debug_check && stats->b_debug_failure &&
stats->b_debug_recover)
rc = 0;

out:
if (rc)
ocfs2_blockcheck_debug_remove(stats);
return rc;
}
#else
static inline int ocfs2_blockcheck_debug_install(struct ocfs2_blockcheck_stats *stats,
struct dentry *parent)
{
return 0;
}

static inline void ocfs2_blockcheck_debug_remove(struct ocfs2_blockcheck_stats *stats)
{
}
#endif /* CONFIG_DEBUG_FS */

/* Always-called wrappers for starting and stopping the debugfs files */
int ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats,
struct dentry *parent)
{
return ocfs2_blockcheck_debug_install(stats, parent);
}

void ocfs2_blockcheck_stats_debugfs_remove(struct ocfs2_blockcheck_stats *stats)
{
ocfs2_blockcheck_debug_remove(stats);
}

static void ocfs2_blockcheck_inc_check(struct ocfs2_blockcheck_stats *stats)
{
u64 new_count;

if (!stats)
return;

spin_lock(&stats->b_lock);
stats->b_check_count++;
new_count = stats->b_check_count;
spin_unlock(&stats->b_lock);

if (!new_count)
mlog(ML_NOTICE, "Block check count has wrapped\n");
}

static void ocfs2_blockcheck_inc_failure(struct ocfs2_blockcheck_stats *stats)
{
u64 new_count;

if (!stats)
return;

spin_lock(&stats->b_lock);
stats->b_failure_count++;
new_count = stats->b_failure_count;
spin_unlock(&stats->b_lock);

if (!new_count)
mlog(ML_NOTICE, "Checksum failure count has wrapped\n");
}

static void ocfs2_blockcheck_inc_recover(struct ocfs2_blockcheck_stats *stats)
{
u64 new_count;

if (!stats)
return;

spin_lock(&stats->b_lock);
stats->b_recover_count++;
new_count = stats->b_recover_count;
spin_unlock(&stats->b_lock);

if (!new_count)
mlog(ML_NOTICE, "ECC recovery count has wrapped\n");
}



/*
* These are the low-level APIs for using the ocfs2_block_check structure.
*/

/*
* This function generates check information for a block.
* data is the block to be checked. bc is a pointer to the
Expand Down Expand Up @@ -266,12 +418,15 @@ void ocfs2_block_check_compute(void *data, size_t blocksize,
* Again, the data passed in should be the on-disk endian.
*/
int ocfs2_block_check_validate(void *data, size_t blocksize,
struct ocfs2_block_check *bc)
struct ocfs2_block_check *bc,
struct ocfs2_blockcheck_stats *stats)
{
int rc = 0;
struct ocfs2_block_check check;
u32 crc, ecc;

ocfs2_blockcheck_inc_check(stats);

check.bc_crc32e = le32_to_cpu(bc->bc_crc32e);
check.bc_ecc = le16_to_cpu(bc->bc_ecc);

Expand All @@ -282,6 +437,7 @@ int ocfs2_block_check_validate(void *data, size_t blocksize,
if (crc == check.bc_crc32e)
goto out;

ocfs2_blockcheck_inc_failure(stats);
mlog(ML_ERROR,
"CRC32 failed: stored: %u, computed %u. Applying ECC.\n",
(unsigned int)check.bc_crc32e, (unsigned int)crc);
Expand All @@ -292,8 +448,10 @@ int ocfs2_block_check_validate(void *data, size_t blocksize,

/* And check the crc32 again */
crc = crc32_le(~0, data, blocksize);
if (crc == check.bc_crc32e)
if (crc == check.bc_crc32e) {
ocfs2_blockcheck_inc_recover(stats);
goto out;
}

mlog(ML_ERROR, "Fixed CRC32 failed: stored: %u, computed %u\n",
(unsigned int)check.bc_crc32e, (unsigned int)crc);
Expand Down Expand Up @@ -366,7 +524,8 @@ void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
* Again, the data passed in should be the on-disk endian.
*/
int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
struct ocfs2_block_check *bc)
struct ocfs2_block_check *bc,
struct ocfs2_blockcheck_stats *stats)
{
int i, rc = 0;
struct ocfs2_block_check check;
Expand All @@ -377,6 +536,8 @@ int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
if (!nr)
return 0;

ocfs2_blockcheck_inc_check(stats);

check.bc_crc32e = le32_to_cpu(bc->bc_crc32e);
check.bc_ecc = le16_to_cpu(bc->bc_ecc);

Expand All @@ -388,6 +549,7 @@ int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
if (crc == check.bc_crc32e)
goto out;

ocfs2_blockcheck_inc_failure(stats);
mlog(ML_ERROR,
"CRC32 failed: stored: %u, computed %u. Applying ECC.\n",
(unsigned int)check.bc_crc32e, (unsigned int)crc);
Expand Down Expand Up @@ -416,8 +578,10 @@ int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
/* And check the crc32 again */
for (i = 0, crc = ~0; i < nr; i++)
crc = crc32_le(crc, bhs[i]->b_data, bhs[i]->b_size);
if (crc == check.bc_crc32e)
if (crc == check.bc_crc32e) {
ocfs2_blockcheck_inc_recover(stats);
goto out;
}

mlog(ML_ERROR, "Fixed CRC32 failed: stored: %u, computed %u\n",
(unsigned int)check.bc_crc32e, (unsigned int)crc);
Expand Down Expand Up @@ -448,9 +612,11 @@ int ocfs2_validate_meta_ecc(struct super_block *sb, void *data,
struct ocfs2_block_check *bc)
{
int rc = 0;
struct ocfs2_super *osb = OCFS2_SB(sb);

if (ocfs2_meta_ecc(OCFS2_SB(sb)))
rc = ocfs2_block_check_validate(data, sb->s_blocksize, bc);
if (ocfs2_meta_ecc(osb))
rc = ocfs2_block_check_validate(data, sb->s_blocksize, bc,
&osb->osb_ecc_stats);

return rc;
}
Expand All @@ -468,9 +634,11 @@ int ocfs2_validate_meta_ecc_bhs(struct super_block *sb,
struct ocfs2_block_check *bc)
{
int rc = 0;
struct ocfs2_super *osb = OCFS2_SB(sb);

if (ocfs2_meta_ecc(OCFS2_SB(sb)))
rc = ocfs2_block_check_validate_bhs(bhs, nr, bc);
if (ocfs2_meta_ecc(osb))
rc = ocfs2_block_check_validate_bhs(bhs, nr, bc,
&osb->osb_ecc_stats);

return rc;
}
Expand Down
29 changes: 27 additions & 2 deletions fs/ocfs2/blockcheck.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,24 @@
#define OCFS2_BLOCKCHECK_H


/* Count errors and error correction from blockcheck.c */
struct ocfs2_blockcheck_stats {
spinlock_t b_lock;
u64 b_check_count; /* Number of blocks we've checked */
u64 b_failure_count; /* Number of failed checksums */
u64 b_recover_count; /* Number of blocks fixed by ecc */

/*
* debugfs entries, used if this is passed to
* ocfs2_blockcheck_stats_debugfs_install()
*/
struct dentry *b_debug_dir; /* Parent of the debugfs files */
struct dentry *b_debug_check; /* Exposes b_check_count */
struct dentry *b_debug_failure; /* Exposes b_failure_count */
struct dentry *b_debug_recover; /* Exposes b_recover_count */
};


/* High level block API */
void ocfs2_compute_meta_ecc(struct super_block *sb, void *data,
struct ocfs2_block_check *bc);
Expand All @@ -37,11 +55,18 @@ int ocfs2_validate_meta_ecc_bhs(struct super_block *sb,
void ocfs2_block_check_compute(void *data, size_t blocksize,
struct ocfs2_block_check *bc);
int ocfs2_block_check_validate(void *data, size_t blocksize,
struct ocfs2_block_check *bc);
struct ocfs2_block_check *bc,
struct ocfs2_blockcheck_stats *stats);
void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
struct ocfs2_block_check *bc);
int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
struct ocfs2_block_check *bc);
struct ocfs2_block_check *bc,
struct ocfs2_blockcheck_stats *stats);

/* Debug Initialization */
int ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats,
struct dentry *parent);
void ocfs2_blockcheck_stats_debugfs_remove(struct ocfs2_blockcheck_stats *stats);

/*
* Hamming code functions
Expand Down
4 changes: 4 additions & 0 deletions fs/ocfs2/ocfs2.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,9 @@
#include "ocfs2_fs.h"
#include "ocfs2_lockid.h"

/* For struct ocfs2_blockcheck_stats */
#include "blockcheck.h"

/* Most user visible OCFS2 inodes will have very few pieces of
* metadata, but larger files (including bitmaps, etc) must be taken
* into account when designing an access scheme. We allow a small
Expand Down Expand Up @@ -305,6 +308,7 @@ struct ocfs2_super
struct ocfs2_dinode *local_alloc_copy;
struct ocfs2_quota_recovery *quota_rec;

struct ocfs2_blockcheck_stats osb_ecc_stats;
struct ocfs2_alloc_stats alloc_stats;
char dev_str[20]; /* "major,minor" of the device */

Expand Down
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