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dm mpath: push path selector locking down to path selectors
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Proper locking of the lists used by the path selectors should be handled
within the selectors (relying on dm-mpath.c code's use of the m->lock
spinlock was reckless).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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@snitm
snitm committed Feb 23, 2016
1 parent 21136f8 commit 9659f81
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Showing 3 changed files with 59 additions and 11 deletions.
23 changes: 20 additions & 3 deletions drivers/md/dm-queue-length.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
struct selector {
struct list_head valid_paths;
struct list_head failed_paths;
spinlock_t lock;
};

struct path_info {
Expand All @@ -45,6 +46,7 @@ static struct selector *alloc_selector(void)
if (s) {
INIT_LIST_HEAD(&s->valid_paths);
INIT_LIST_HEAD(&s->failed_paths);
spin_lock_init(&s->lock);
}

return s;
Expand Down Expand Up @@ -113,6 +115,7 @@ static int ql_add_path(struct path_selector *ps, struct dm_path *path,
struct path_info *pi;
unsigned repeat_count = QL_MIN_IO;
char dummy;
unsigned long flags;

/*
* Arguments: [<repeat_count>]
Expand Down Expand Up @@ -147,7 +150,9 @@ static int ql_add_path(struct path_selector *ps, struct dm_path *path,

path->pscontext = pi;

spin_lock_irqsave(&s->lock, flags);
list_add_tail(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);

return 0;
}
Expand All @@ -156,16 +161,22 @@ static void ql_fail_path(struct path_selector *ps, struct dm_path *path)
{
struct selector *s = ps->context;
struct path_info *pi = path->pscontext;
unsigned long flags;

spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->failed_paths);
spin_unlock_irqrestore(&s->lock, flags);
}

static int ql_reinstate_path(struct path_selector *ps, struct dm_path *path)
{
struct selector *s = ps->context;
struct path_info *pi = path->pscontext;
unsigned long flags;

spin_lock_irqsave(&s->lock, flags);
list_move_tail(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);

return 0;
}
Expand All @@ -178,9 +189,12 @@ static struct dm_path *ql_select_path(struct path_selector *ps,
{
struct selector *s = ps->context;
struct path_info *pi = NULL, *best = NULL;
struct dm_path *ret = NULL;
unsigned long flags;

spin_lock_irqsave(&s->lock, flags);
if (list_empty(&s->valid_paths))
return NULL;
goto out;

/* Change preferred (first in list) path to evenly balance. */
list_move_tail(s->valid_paths.next, &s->valid_paths);
Expand All @@ -195,11 +209,14 @@ static struct dm_path *ql_select_path(struct path_selector *ps,
}

if (!best)
return NULL;
goto out;

*repeat_count = best->repeat_count;

return best->path;
ret = best->path;
out:
spin_unlock_irqrestore(&s->lock, flags);
return ret;
}

static int ql_start_io(struct path_selector *ps, struct dm_path *path,
Expand Down
24 changes: 19 additions & 5 deletions drivers/md/dm-round-robin.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ static void free_paths(struct list_head *paths)
struct selector {
struct list_head valid_paths;
struct list_head invalid_paths;
spinlock_t lock;
};

static struct selector *alloc_selector(void)
Expand All @@ -55,6 +56,7 @@ static struct selector *alloc_selector(void)
if (s) {
INIT_LIST_HEAD(&s->valid_paths);
INIT_LIST_HEAD(&s->invalid_paths);
spin_lock_init(&s->lock);
}

return s;
Expand All @@ -74,7 +76,7 @@ static int rr_create(struct path_selector *ps, unsigned argc, char **argv)

static void rr_destroy(struct path_selector *ps)
{
struct selector *s = (struct selector *) ps->context;
struct selector *s = ps->context;

free_paths(&s->valid_paths);
free_paths(&s->invalid_paths);
Expand Down Expand Up @@ -111,10 +113,11 @@ static int rr_status(struct path_selector *ps, struct dm_path *path,
static int rr_add_path(struct path_selector *ps, struct dm_path *path,
int argc, char **argv, char **error)
{
struct selector *s = (struct selector *) ps->context;
struct selector *s = ps->context;
struct path_info *pi;
unsigned repeat_count = RR_MIN_IO;
char dummy;
unsigned long flags;

if (argc > 1) {
*error = "round-robin ps: incorrect number of arguments";
Expand Down Expand Up @@ -144,40 +147,51 @@ static int rr_add_path(struct path_selector *ps, struct dm_path *path,

path->pscontext = pi;

spin_lock_irqsave(&s->lock, flags);
list_add_tail(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);

return 0;
}

static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
{
struct selector *s = (struct selector *) ps->context;
unsigned long flags;
struct selector *s = ps->context;
struct path_info *pi = p->pscontext;

spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->invalid_paths);
spin_unlock_irqrestore(&s->lock, flags);
}

static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
{
struct selector *s = (struct selector *) ps->context;
unsigned long flags;
struct selector *s = ps->context;
struct path_info *pi = p->pscontext;

spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);

return 0;
}

static struct dm_path *rr_select_path(struct path_selector *ps,
unsigned *repeat_count, size_t nr_bytes)
{
struct selector *s = (struct selector *) ps->context;
unsigned long flags;
struct selector *s = ps->context;
struct path_info *pi = NULL;

spin_lock_irqsave(&s->lock, flags);
if (!list_empty(&s->valid_paths)) {
pi = list_entry(s->valid_paths.next, struct path_info, list);
list_move_tail(&pi->list, &s->valid_paths);
*repeat_count = pi->repeat_count;
}
spin_unlock_irqrestore(&s->lock, flags);

return pi ? pi->path : NULL;
}
Expand Down
23 changes: 20 additions & 3 deletions drivers/md/dm-service-time.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
struct selector {
struct list_head valid_paths;
struct list_head failed_paths;
spinlock_t lock;
};

struct path_info {
Expand All @@ -41,6 +42,7 @@ static struct selector *alloc_selector(void)
if (s) {
INIT_LIST_HEAD(&s->valid_paths);
INIT_LIST_HEAD(&s->failed_paths);
spin_lock_init(&s->lock);
}

return s;
Expand Down Expand Up @@ -111,6 +113,7 @@ static int st_add_path(struct path_selector *ps, struct dm_path *path,
unsigned repeat_count = ST_MIN_IO;
unsigned relative_throughput = 1;
char dummy;
unsigned long flags;

/*
* Arguments: [<repeat_count> [<relative_throughput>]]
Expand Down Expand Up @@ -160,7 +163,9 @@ static int st_add_path(struct path_selector *ps, struct dm_path *path,

path->pscontext = pi;

spin_lock_irqsave(&s->lock, flags);
list_add_tail(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);

return 0;
}
Expand All @@ -169,16 +174,22 @@ static void st_fail_path(struct path_selector *ps, struct dm_path *path)
{
struct selector *s = ps->context;
struct path_info *pi = path->pscontext;
unsigned long flags;

spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->failed_paths);
spin_unlock_irqrestore(&s->lock, flags);
}

static int st_reinstate_path(struct path_selector *ps, struct dm_path *path)
{
struct selector *s = ps->context;
struct path_info *pi = path->pscontext;
unsigned long flags;

spin_lock_irqsave(&s->lock, flags);
list_move_tail(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);

return 0;
}
Expand Down Expand Up @@ -265,9 +276,12 @@ static struct dm_path *st_select_path(struct path_selector *ps,
{
struct selector *s = ps->context;
struct path_info *pi = NULL, *best = NULL;
struct dm_path *ret = NULL;
unsigned long flags;

spin_lock_irqsave(&s->lock, flags);
if (list_empty(&s->valid_paths))
return NULL;
goto out;

/* Change preferred (first in list) path to evenly balance. */
list_move_tail(s->valid_paths.next, &s->valid_paths);
Expand All @@ -277,11 +291,14 @@ static struct dm_path *st_select_path(struct path_selector *ps,
best = pi;

if (!best)
return NULL;
goto out;

*repeat_count = best->repeat_count;

return best->path;
ret = best->path;
out:
spin_unlock_irqrestore(&s->lock, flags);
return ret;
}

static int st_start_io(struct path_selector *ps, struct dm_path *path,
Expand Down

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