diff options
Diffstat (limited to 'block/raw-posix.c')
| -rw-r--r-- | block/raw-posix.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/block/raw-posix.c b/block/raw-posix.c index dacf4fbbc8..825a0c878f 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -55,6 +55,9 @@ #include <linux/cdrom.h> #include <linux/fd.h> #include <linux/fs.h> +#ifndef FS_NOCOW_FL +#define FS_NOCOW_FL 0x00800000 /* Do not cow file */ +#endif #endif #ifdef CONFIG_FIEMAP #include <linux/fiemap.h> @@ -1278,12 +1281,14 @@ static int raw_create(const char *filename, QemuOpts *opts, Error **errp) int fd; int result = 0; int64_t total_size = 0; + bool nocow = false; strstart(filename, "file:", &filename); /* Read out options */ total_size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0) / BDRV_SECTOR_SIZE; + nocow = qemu_opt_get_bool(opts, BLOCK_OPT_NOCOW, false); fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644); @@ -1291,6 +1296,21 @@ static int raw_create(const char *filename, QemuOpts *opts, Error **errp) result = -errno; error_setg_errno(errp, -result, "Could not create file"); } else { + if (nocow) { +#ifdef __linux__ + /* Set NOCOW flag to solve performance issue on fs like btrfs. + * This is an optimisation. The FS_IOC_SETFLAGS ioctl return value + * will be ignored since any failure of this operation should not + * block the left work. + */ + int attr; + if (ioctl(fd, FS_IOC_GETFLAGS, &attr) == 0) { + attr |= FS_NOCOW_FL; + ioctl(fd, FS_IOC_SETFLAGS, &attr); + } +#endif + } + if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) { result = -errno; error_setg_errno(errp, -result, "Could not resize file"); @@ -1477,6 +1497,11 @@ static QemuOptsList raw_create_opts = { .type = QEMU_OPT_SIZE, .help = "Virtual disk size" }, + { + .name = BLOCK_OPT_NOCOW, + .type = QEMU_OPT_BOOL, + .help = "Turn off copy-on-write (valid only on btrfs)" + }, { /* end of list */ } } }; |