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label: Add label_read callback.

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This commit is contained in:
Alasdair G Kergon 2018-01-08 23:08:22 +00:00
parent 6d322e68f3
commit 4b02d4e22e
3 changed files with 52 additions and 9 deletions
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15
lib/cache/lvmcache.c vendored
View File

@ -1095,6 +1095,14 @@ next:
goto next;
}
/* Track the number of outstanding label reads */
static void _process_label_data(int failed, void *context, void *data)
{
int *nr_labels_outstanding = context;
(*nr_labels_outstanding)--;
}
int lvmcache_label_scan(struct cmd_context *cmd)
{
struct dm_list del_cache_devs;
@ -1106,6 +1114,7 @@ int lvmcache_label_scan(struct cmd_context *cmd)
struct device *dev;
struct format_type *fmt;
int dev_count = 0;
int nr_labels_outstanding = 0;
int r = 0;
@ -1144,13 +1153,15 @@ int lvmcache_label_scan(struct cmd_context *cmd)
_destroy_duplicate_device_list(&_found_duplicate_devs);
while ((dev = dev_iter_get(iter))) {
(void) label_read(dev, &label, UINT64_C(0));
nr_labels_outstanding++;
if (!label_read_callback(cmd->mem, dev, UINT64_C(0), _process_label_data, &nr_labels_outstanding))
nr_labels_outstanding--;
dev_count++;
}
dev_iter_destroy(iter);
log_very_verbose("Scanned %d device labels", dev_count);
log_very_verbose("Scanned %d device labels (%d outstanding)", dev_count, nr_labels_outstanding);
/*
* _choose_preferred_devs() returns:

44
lib/label/label.c
View File

@ -122,8 +122,10 @@ static void _update_lvmcache_orphan(struct lvmcache_info *info)
struct find_labeller_params {
struct device *dev;
uint64_t scan_sector; /* Sector to be scanned */
uint64_t label_sector; /* Sector where label found */
lvm_callback_fn_t process_label_data_fn;
void *process_label_data_context;
struct label **result;
int ret;
@ -134,8 +136,10 @@ static void _set_label_read_result(int failed, void *context, void *data)
struct find_labeller_params *flp = context;
struct label **result = flp->result;
if (failed)
if (failed) {
flp->ret = 0;
goto_out;
}
if (result && *result) {
(*result)->dev = flp->dev;
@ -145,6 +149,9 @@ static void _set_label_read_result(int failed, void *context, void *data)
out:
if (!dev_close(flp->dev))
stack;
if (flp->ret && flp->process_label_data_fn)
flp->process_label_data_fn(0, flp->process_label_data_context, NULL);
}
static void _find_labeller(int failed, void *context, void *data)
@ -161,6 +168,12 @@ static void _find_labeller(int failed, void *context, void *data)
struct lvmcache_info *info;
uint64_t sector;
if (failed) {
log_debug_devs("%s: Failed to read label area", dev_name(dev));
_set_label_read_result(1, flp, NULL);
return;
}
/* Scan a few sectors for a valid label */
for (sector = 0; sector < LABEL_SCAN_SECTORS;
sector += LABEL_SIZE >> SECTOR_SHIFT) {
@ -222,7 +235,7 @@ static void _find_labeller(int failed, void *context, void *data)
flp->ret = 0;
_set_label_read_result(1, flp, NULL);
} else
flp->ret = (l->ops->read)(l, dev, labelbuf, result, &_set_label_read_result, flp);
(void) (l->ops->read)(l, dev, labelbuf, result, &_set_label_read_result, flp);
}
/* FIXME Also wipe associated metadata area headers? */
@ -300,7 +313,8 @@ int label_remove(struct device *dev)
return r;
}
static int _label_read(struct device *dev, uint64_t scan_sector, struct label **result)
static int _label_read(struct device *dev, uint64_t scan_sector, struct label **result,
lvm_callback_fn_t process_label_data_fn, void *process_label_data_context)
{
struct lvmcache_info *info;
struct find_labeller_params *flp;
@ -309,6 +323,8 @@ static int _label_read(struct device *dev, uint64_t scan_sector, struct label **
if ((info = lvmcache_info_from_pvid(dev->pvid, dev, 1))) {
log_debug_devs("Reading label from lvmcache for %s", dev_name(dev));
*result = lvmcache_get_label(info);
if (process_label_data_fn)
process_label_data_fn(0, process_label_data_context, NULL);
return 1;
}
@ -320,6 +336,8 @@ static int _label_read(struct device *dev, uint64_t scan_sector, struct label **
flp->dev = dev;
flp->scan_sector = scan_sector;
flp->result = result;
flp->process_label_data_fn = process_label_data_fn;
flp->process_label_data_context = process_label_data_context;
flp->ret = 1;
/* Ensure result is always wiped as a precaution */
@ -337,19 +355,31 @@ static int _label_read(struct device *dev, uint64_t scan_sector, struct label **
return 0;
}
if (!(readbuf = dev_read(dev, scan_sector << SECTOR_SHIFT, LABEL_SCAN_SIZE, DEV_IO_LABEL))) {
if (!(dev_read_callback(dev, scan_sector << SECTOR_SHIFT, LABEL_SCAN_SIZE, DEV_IO_LABEL, _find_labeller, flp))) {
log_debug_devs("%s: Failed to read label area", dev_name(dev));
_set_label_read_result(1, flp, NULL);
return 0;
}
_find_labeller(0, flp, readbuf);
return flp->ret;
}
int label_read(struct device *dev, struct label **result, uint64_t scan_sector)
{
return _label_read(dev, scan_sector, result);
return _label_read(dev, scan_sector, result, NULL, NULL);
}
int label_read_callback(struct dm_pool *mem, struct device *dev, uint64_t scan_sector,
lvm_callback_fn_t process_label_data_fn, void *process_label_data_context)
{
struct label **result; /* FIXME Eliminate this */
if (!(result = dm_zalloc(sizeof(*result)))) {
log_error("Couldn't allocate memory for internal result pointer.");
return 0;
}
return _label_read(dev, scan_sector, result, process_label_data_fn, process_label_data_context);
}
/* Caller may need to use label_get_handler to create label struct! */

2
lib/label/label.h
View File

@ -96,6 +96,8 @@ struct labeller *label_get_handler(const char *name);
int label_remove(struct device *dev);
int label_read(struct device *dev, struct label **result,
uint64_t scan_sector);
int label_read_callback(struct dm_pool *mem, struct device *dev, uint64_t scan_sector,
lvm_callback_fn_t process_label_data_fn, void *process_label_data_context);
int label_write(struct device *dev, struct label *label);
struct label *label_create(struct labeller *labeller);
void label_destroy(struct label *label);