diff options
Diffstat (limited to 'block/vdi.c')
| -rw-r--r-- | block/vdi.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/block/vdi.c b/block/vdi.c index 01fe22ebe8..197bd77c97 100644 --- a/block/vdi.c +++ b/block/vdi.c @@ -53,6 +53,13 @@ #include "block/block_int.h" #include "qemu/module.h" #include "migration/migration.h" +#ifdef __linux__ +#include <linux/fs.h> +#include <sys/ioctl.h> +#ifndef FS_NOCOW_FL +#define FS_NOCOW_FL 0x00800000 /* Do not cow file */ +#endif +#endif #if defined(CONFIG_UUID) #include <uuid/uuid.h> @@ -683,6 +690,7 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp) VdiHeader header; size_t i; size_t bmap_size; + bool nocow = false; logout("\n"); @@ -699,6 +707,7 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp) image_type = VDI_TYPE_STATIC; } #endif + nocow = qemu_opt_get_bool_del(opts, BLOCK_OPT_NOCOW, false); if (bytes > VDI_DISK_SIZE_MAX) { result = -ENOTSUP; @@ -716,6 +725,21 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp) goto exit; } + 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 + } + /* We need enough blocks to store the given disk size, so always round up. */ blocks = (bytes + block_size - 1) / block_size; @@ -818,6 +842,11 @@ static QemuOptsList vdi_create_opts = { .def_value_str = "off" }, #endif + { + .name = BLOCK_OPT_NOCOW, + .type = QEMU_OPT_BOOL, + .help = "Turn off copy-on-write (valid only on btrfs)" + }, /* TODO: An additional option to set UUID values might be useful. */ { /* end of list */ } } |