diff options
Diffstat (limited to 'block/vpc.c')
| -rw-r--r-- | block/vpc.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/block/vpc.c b/block/vpc.c index 798d8540db..8b376a40be 100644 --- a/block/vpc.c +++ b/block/vpc.c @@ -29,6 +29,13 @@ #if defined(CONFIG_UUID) #include <uuid/uuid.h> #endif +#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 /**************************************************************/ @@ -751,6 +758,7 @@ static int vpc_create(const char *filename, QemuOpts *opts, Error **errp) int64_t total_size; int disk_type; int ret = -EIO; + bool nocow = false; /* Read out options */ total_size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); @@ -767,6 +775,7 @@ static int vpc_create(const char *filename, QemuOpts *opts, Error **errp) } else { disk_type = VHD_DYNAMIC; } + nocow = qemu_opt_get_bool_del(opts, BLOCK_OPT_NOCOW, false); /* Create the file */ fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644); @@ -775,6 +784,21 @@ static int vpc_create(const char *filename, QemuOpts *opts, Error **errp) goto out; } + 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 + } + /* * Calculate matching total_size and geometry. Increase the number of * sectors requested until we get enough (or fail). This ensures that @@ -884,6 +908,11 @@ static QemuOptsList vpc_create_opts = { "Type of virtual hard disk format. Supported formats are " "{dynamic (default) | fixed} " }, + { + .name = BLOCK_OPT_NOCOW, + .type = QEMU_OPT_BOOL, + .help = "Turn off copy-on-write (valid only on btrfs)" + }, { /* end of list */ } } }; |