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Fixes for procfs files backed by linked lists

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There are some issues with the way the seq_file interface is implemented
for kstats backed by linked lists (zfs_dbgmsgs and certain per-pool
debugging info):

* We don't account for the fact that seq_file sometimes visits a node
  multiple times, which results in missing messages when read through
  procfs.
* We don't keep separate state for each reader of a file, so concurrent
  readers will receive incorrect results.
* We don't account for the fact that entries may have been removed from
  the list between read syscalls, so reading from these files in procfs
  can cause the system to crash.

This change fixes these issues and adds procfs_list, a wrapper around a
linked list which abstracts away the details of implementing the
seq_file interface for a list and exposing the contents of the list
through procfs.

Reviewed by: Don Brady <don.brady@delphix.com>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: John Gallagher <john.gallagher@delphix.com>
External-issue: LX-1211
Closes #7819
This commit is contained in:
John Gallagher
2018-09-26 11:08:12 -07:00
committed by Brian Behlendorf
parent 3ed2fbcc1c
commit d12614521a
24 changed files with 1094 additions and 566 deletions
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include/sys/spa.h
+14 -9
View File
@@ -863,22 +863,27 @@ extern boolean_t spa_refcount_zero(spa_t *spa);
#define SCL_STATE_ALL (SCL_STATE | SCL_L2ARC | SCL_ZIO)
/* Historical pool statistics */
typedef struct spa_stats_history {
typedef struct spa_history_kstat {
kmutex_t lock;
uint64_t count;
uint64_t size;
kstat_t *kstat;
void *private;
list_t list;
} spa_stats_history_t;
} spa_history_kstat_t;
typedef struct spa_history_list {
uint64_t size;
procfs_list_t procfs_list;
} spa_history_list_t;
typedef struct spa_stats {
spa_stats_history_t read_history;
spa_stats_history_t txg_history;
spa_stats_history_t tx_assign_histogram;
spa_stats_history_t io_history;
spa_stats_history_t mmp_history;
spa_stats_history_t state; /* pool state */
spa_history_list_t read_history;
spa_history_list_t txg_history;
spa_history_kstat_t tx_assign_histogram;
spa_history_kstat_t io_history;
spa_history_list_t mmp_history;
spa_history_kstat_t state; /* pool state */
} spa_stats_t;
typedef enum txg_state {
@@ -911,7 +916,7 @@ extern void spa_tx_assign_add_nsecs(spa_t *spa, uint64_t nsecs);
extern int spa_mmp_history_set_skip(spa_t *spa, uint64_t mmp_kstat_id);
extern int spa_mmp_history_set(spa_t *spa, uint64_t mmp_kstat_id, int io_error,
hrtime_t duration);
extern void *spa_mmp_history_add(spa_t *spa, uint64_t txg, uint64_t timestamp,
extern void spa_mmp_history_add(spa_t *spa, uint64_t txg, uint64_t timestamp,
uint64_t mmp_delay, vdev_t *vd, int label, uint64_t mmp_kstat_id,
int error);