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author | Richard Weinberger <richard@nod.at> | 2013-08-18 13:30:06 +0200 |
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committer | Richard Weinberger <richard@nod.at> | 2013-09-07 10:56:49 +0200 |
commit | 805f11a0d515658106bfbfadceff0eb30bd90ad2 (patch) | |
tree | 2bcfbc9028d5a92875272302bd9e7daf82b4e4be /arch/um | |
parent | f75b1b1bedfb498cc43a992ce4d7ed8df3b1e770 (diff) | |
download | linux-stable-805f11a0d515658106bfbfadceff0eb30bd90ad2.tar.gz linux-stable-805f11a0d515658106bfbfadceff0eb30bd90ad2.tar.bz2 linux-stable-805f11a0d515658106bfbfadceff0eb30bd90ad2.zip |
um: ubd: Add REQ_FLUSH suppport
UML's block device driver does not support write barriers,
to support this this patch adds REQ_FLUSH suppport.
Every time the block layer sends a REQ_FLUSH we fsync() now
our backing file to guarantee data consistency.
Reported-and-tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um')
-rw-r--r-- | arch/um/drivers/ubd_kern.c | 41 | ||||
-rw-r--r-- | arch/um/include/shared/os.h | 1 | ||||
-rw-r--r-- | arch/um/os-Linux/file.c | 9 |
3 files changed, 50 insertions, 1 deletions
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c index 879990cb66c6..d27c703be1a1 100644 --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -41,7 +41,7 @@ #include <os.h> #include "cow.h" -enum ubd_req { UBD_READ, UBD_WRITE }; +enum ubd_req { UBD_READ, UBD_WRITE, UBD_FLUSH }; struct io_thread_req { struct request *req; @@ -866,6 +866,7 @@ static int ubd_add(int n, char **error_out) goto out; } ubd_dev->queue->queuedata = ubd_dev; + blk_queue_flush(ubd_dev->queue, REQ_FLUSH); blk_queue_max_segments(ubd_dev->queue, MAX_SG); err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]); @@ -1239,6 +1240,19 @@ static void prepare_request(struct request *req, struct io_thread_req *io_req, } /* Called with dev->lock held */ +static void prepare_flush_request(struct request *req, + struct io_thread_req *io_req) +{ + struct gendisk *disk = req->rq_disk; + struct ubd *ubd_dev = disk->private_data; + + io_req->req = req; + io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : + ubd_dev->fd; + io_req->op = UBD_FLUSH; +} + +/* Called with dev->lock held */ static void do_ubd_request(struct request_queue *q) { struct io_thread_req *io_req; @@ -1259,6 +1273,20 @@ static void do_ubd_request(struct request_queue *q) } req = dev->request; + + if (req->cmd_flags & REQ_FLUSH) { + io_req = kmalloc(sizeof(struct io_thread_req), + GFP_ATOMIC); + if (io_req == NULL) { + if (list_empty(&dev->restart)) + list_add(&dev->restart, &restart); + return; + } + prepare_flush_request(req, io_req); + os_write_file(thread_fd, &io_req, + sizeof(struct io_thread_req *)); + } + while(dev->start_sg < dev->end_sg){ struct scatterlist *sg = &dev->sg[dev->start_sg]; @@ -1367,6 +1395,17 @@ static void do_io(struct io_thread_req *req) int err; __u64 off; + if (req->op == UBD_FLUSH) { + /* fds[0] is always either the rw image or our cow file */ + n = os_sync_file(req->fds[0]); + if (n != 0) { + printk("do_io - sync failed err = %d " + "fd = %d\n", -n, req->fds[0]); + req->error = 1; + } + return; + } + nsectors = req->length / req->sectorsize; start = 0; do { diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index c70a234a3f8c..e98303925cc5 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -141,6 +141,7 @@ extern int os_seek_file(int fd, unsigned long long offset); extern int os_open_file(const char *file, struct openflags flags, int mode); extern int os_read_file(int fd, void *buf, int len); extern int os_write_file(int fd, const void *buf, int count); +extern int os_sync_file(int fd); extern int os_file_size(const char *file, unsigned long long *size_out); extern int os_file_modtime(const char *file, unsigned long *modtime); extern int os_pipe(int *fd, int stream, int close_on_exec); diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c index c17bd6f7d674..07a750197bb0 100644 --- a/arch/um/os-Linux/file.c +++ b/arch/um/os-Linux/file.c @@ -266,6 +266,15 @@ int os_write_file(int fd, const void *buf, int len) return n; } +int os_sync_file(int fd) +{ + int n = fsync(fd); + + if (n < 0) + return -errno; + return n; +} + int os_file_size(const char *file, unsigned long long *size_out) { struct uml_stat buf; |