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f3probe: fix a (supposed) race condition

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Although I (Michel) am not 100% sure, the kernel seemed to be
allowing reads to get data from an internal cache in the kernel;
the condition is tricky to reproduce, and trickier to be sure
since fake drives are not reliable or preditable.
The results seems more stable with this patch, though.
This commit is contained in:
Michel Machado 2015-11-13 20:18:12 -05:00
parent bf550a0ce9
commit cedb3f17d2
1 changed files with 9 additions and 2 deletions
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11
libdevs.c
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@ -444,15 +444,22 @@ static int bdev_write_blocks(struct device *dev, const char *buf,
size_t length = (last_pos - first_pos + 1) << block_order; size_t length = (last_pos - first_pos + 1) << block_order;
off_t offset = first_pos << block_order; off_t offset = first_pos << block_order;
off_t off_ret = lseek(bdev->fd, offset, SEEK_SET); off_t off_ret = lseek(bdev->fd, offset, SEEK_SET);
int rc;
if (off_ret < 0) if (off_ret < 0)
return - errno; return - errno;
assert(off_ret == offset); assert(off_ret == offset);
return write_all(bdev->fd, buf, length); rc = write_all(bdev->fd, buf, length);
if (rc)
return rc;
rc = fsync(bdev->fd);
if (rc)
return rc;
return posix_fadvise(bdev->fd, 0, 0, POSIX_FADV_DONTNEED);
} }
static inline int bdev_open(const char *filename) static inline int bdev_open(const char *filename)
{ {
return open(filename, O_RDWR | O_DIRECT | O_SYNC); return open(filename, O_RDWR | O_DIRECT);
} }
static struct udev_device *map_dev_to_usb_dev(struct udev_device *dev) static struct udev_device *map_dev_to_usb_dev(struct udev_device *dev)