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scan: work around udev problems by avoiding open RDWR

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udev creates a train wreck of events if we open devices
with RDWR.  Until we can fix/disable/scrap udev, work around
this by opening RDONLY and then closing/reopening RDWR when
a write is needed.  This invalidates the bcache blocks for
the device before writing so it can trigger unnecessary
rereading.
This commit is contained in:
David Teigland 2018-06-20 11:32:45 -05:00
parent 76075ff55d
commit a30e622279
2 changed files with 55 additions and 2 deletions
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1
lib/device/device.h
View File

@ -35,6 +35,7 @@
#define DEV_BCACHE_EXCL 0x00001000 /* bcache_fd should be open EXCL */
#define DEV_FILTER_AFTER_SCAN 0x00002000 /* apply filter after bcache has data */
#define DEV_FILTER_OUT_SCAN 0x00004000 /* filtered out during label scan */
#define DEV_BCACHE_WRITE 0x00008000 /* bcache_fd is open with RDWR */
/*
* Support for external device info.

56
lib/label/label.c
View File

@ -464,12 +464,24 @@ static int _scan_dev_open(struct device *dev)
name_sl = dm_list_item(name_list, struct dm_str_list);
name = name_sl->str;
flags |= O_RDWR;
flags |= O_DIRECT;
flags |= O_NOATIME;
if (dev->flags & DEV_BCACHE_EXCL)
/*
* FIXME: udev is a train wreck when we open RDWR and close, so we
* need to only use RDWR when we actually need to write, and use
* RDONLY otherwise. Fix, disable or scrap udev nonsense so we can
* just open with RDWR by default.
*/
if (dev->flags & DEV_BCACHE_EXCL) {
flags |= O_EXCL;
flags |= O_RDWR;
} else if (dev->flags & DEV_BCACHE_WRITE) {
flags |= O_RDWR;
} else {
flags |= O_RDONLY;
}
retry_open:
@ -1107,7 +1119,14 @@ int label_scan_open(struct device *dev)
int label_scan_open_excl(struct device *dev)
{
if (_in_bcache(dev) && !(dev->flags & DEV_BCACHE_EXCL)) {
/* FIXME: avoid tossing out bcache blocks just to replace fd. */
log_debug("Close and reopen excl %s", dev_name(dev));
bcache_invalidate_fd(scan_bcache, dev->bcache_fd);
_scan_dev_close(dev);
}
dev->flags |= DEV_BCACHE_EXCL;
dev->flags |= DEV_BCACHE_WRITE;
return label_scan_open(dev);
}
@ -1149,8 +1168,19 @@ bool dev_write_bytes(struct device *dev, uint64_t start, size_t len, void *data)
return false;
}
if (!(dev->flags & DEV_BCACHE_WRITE)) {
/* FIXME: avoid tossing out bcache blocks just to replace fd. */
log_debug("Close and reopen to write %s", dev_name(dev));
bcache_invalidate_fd(scan_bcache, dev->bcache_fd);
_scan_dev_close(dev);
dev->flags |= DEV_BCACHE_WRITE;
label_scan_open(dev);
}
if (dev->bcache_fd <= 0) {
/* This is not often needed, perhaps only with lvmetad. */
dev->flags |= DEV_BCACHE_WRITE;
if (!label_scan_open(dev)) {
log_error("Error opening device %s for writing at %llu length %u.",
dev_name(dev), (unsigned long long)start, (uint32_t)len);
@ -1184,8 +1214,19 @@ bool dev_write_zeros(struct device *dev, uint64_t start, size_t len)
return false;
}
if (!(dev->flags & DEV_BCACHE_WRITE)) {
/* FIXME: avoid tossing out bcache blocks just to replace fd. */
log_debug("Close and reopen to write %s", dev_name(dev));
bcache_invalidate_fd(scan_bcache, dev->bcache_fd);
_scan_dev_close(dev);
dev->flags |= DEV_BCACHE_WRITE;
label_scan_open(dev);
}
if (dev->bcache_fd <= 0) {
/* This is not often needed, perhaps only with lvmetad. */
dev->flags |= DEV_BCACHE_WRITE;
if (!label_scan_open(dev)) {
log_error("Error opening device %s for writing at %llu length %u.",
dev_name(dev), (unsigned long long)start, (uint32_t)len);
@ -1219,8 +1260,19 @@ bool dev_set_bytes(struct device *dev, uint64_t start, size_t len, uint8_t val)
return false;
}
if (!(dev->flags & DEV_BCACHE_WRITE)) {
/* FIXME: avoid tossing out bcache blocks just to replace fd. */
log_debug("Close and reopen to write %s", dev_name(dev));
bcache_invalidate_fd(scan_bcache, dev->bcache_fd);
_scan_dev_close(dev);
dev->flags |= DEV_BCACHE_WRITE;
label_scan_open(dev);
}
if (dev->bcache_fd <= 0) {
/* This is not often needed, perhaps only with lvmetad. */
dev->flags |= DEV_BCACHE_WRITE;
if (!label_scan_open(dev)) {
log_error("Error opening device %s for writing at %llu length %u.",
dev_name(dev), (unsigned long long)start, (uint32_t)len);