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J. R. Okajima 53d6660836 loop: add ioctl to resize a loop device ... Add the ability to 'resize' the loop device on the fly. One practical application is a loop file with XFS filesystem, already mounted: You can easily enlarge the file (append some bytes) and then call ioctl(fd, LOOP_SET_CAPACITY, new); The loop driver will learn about the new size and you can use xfs_growfs later on, which will allow you to use full capacity of the loop file without the need to unmount. Test app: #include <linux/fs.h> #include <linux/loop.h> #include <sys/ioctl.h> #include <sys/stat.h> #include <sys/types.h> #include <assert.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #define _GNU_SOURCE #include <getopt.h> char *me; void usage(FILE *f) { fprintf(f, "%s [options] loop_dev [backend_file]\n" "-s, --set new_size_in_bytes\n" "\twhen backend_file is given, " "it will be expanded too while keeping the original contents\n", me); } struct option opts[] = { { .name = "set", .has_arg = 1, .flag = NULL, .val = 's' }, { .name = "help", .has_arg = 0, .flag = NULL, .val = 'h' } }; void err_size(char *name, __u64 old) { fprintf(stderr, "size must be larger than current %s (%llu)\n", name, old); } int main(int argc, char *argv[]) { int fd, err, c, i, bfd; ssize_t ssz; size_t sz; __u64 old, new, append; char a[BUFSIZ]; struct stat st; FILE *out; char *backend, *dev; err = EINVAL; out = stderr; me = argv[0]; new = 0; while ((c = getopt_long(argc, argv, "s:h", opts, &i)) != -1) { switch (c) { case 's': errno = 0; new = strtoull(optarg, NULL, 0); if (errno) { err = errno; perror(argv[i]); goto out; } break; case 'h': err = 0; out = stdout; goto err; default: perror(argv[i]); goto err; } } if (optind < argc) dev = argv[optind++]; else goto err; fd = open(dev, O_RDONLY); if (fd < 0) { err = errno; perror(dev); goto out; } err = ioctl(fd, BLKGETSIZE64, &old); if (err) { err = errno; perror("ioctl BLKGETSIZE64"); goto out; } if (!new) { printf("%llu\n", old); goto out; } if (new < old) { err = EINVAL; err_size(dev, old); goto out; } if (optind < argc) { backend = argv[optind++]; bfd = open(backend, O_WRONLY|O_APPEND); if (bfd < 0) { err = errno; perror(backend); goto out; } err = fstat(bfd, &st); if (err) { err = errno; perror(backend); goto out; } if (new < st.st_size) { err = EINVAL; err_size(backend, st.st_size); goto out; } append = new - st.st_size; sz = sizeof(a); while (append > 0) { if (append < sz) sz = append; ssz = write(bfd, a, sz); if (ssz != sz) { err = errno; perror(backend); goto out; } append -= sz; } err = fsync(bfd); if (err) { err = errno; perror(backend); goto out; } } err = ioctl(fd, LOOP_SET_CAPACITY, new); if (err) { err = errno; perror("ioctl LOOP_SET_CAPACITY"); } goto out; err: usage(out); out: return err; } Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp> Signed-off-by: Tomas Matejicek <tomas@slax.org> Cc: <util-linux-ng@vger.kernel.org> Cc: Karel Zak <kzak@redhat.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: <linux-api@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		16 years ago
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accessibility	…
acpi	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
amba	amba: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
ata	Merge branch 'origin' into devel	16 years ago
atm	atm: fix non-const printk argument	16 years ago
auxdisplay	…
base	Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-cpumask	16 years ago
block	loop: add ioctl to resize a loop device	16 years ago
bluetooth	…
cdrom	…
char	proc tty: switch amiserial to ->proc_fops	16 years ago
clocksource	Merge branch 'core/percpu' into percpu-cpumask-x86-for-linus-2	16 years ago
connector	…
cpufreq	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq	16 years ago
cpuidle	…
crypto	Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	16 years ago
dca	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6	16 years ago
dio	dio: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
dma	Merge branch 'origin' into devel	16 years ago
edac	edac: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
eisa	Merge branch 'core/percpu' into percpu-cpumask-x86-for-linus-2	16 years ago
firewire	firewire: core: optimize propagation of BROADCAST_CHANNEL	16 years ago
firmware	dmi: Let dmi_walk() users pass private data	16 years ago
gpio	gpio: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
gpu	drm: detect hdmi monitor by hdmi identifier (v3)	16 years ago
hid	Merge branch 'bkl-removal' of git://git.lwn.net/linux-2.6	16 years ago
hwmon	hwmon: (fschmd) Add support for the FSC Hades IC	16 years ago
i2c	Merge branch 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6	16 years ago
ide	ide: keep track of number of bytes instead of sectors in struct ide_cmd	16 years ago
idle	…
ieee1394	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6	16 years ago
infiniband	Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6	16 years ago
input	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
isdn	proc tty: remove struct tty_operations::read_proc	16 years ago
leds	…
lguest	lguest: use bool instead of int	16 years ago
macintosh	…
mca	mca: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
md	dm crypt: wait for endio to complete before destruction	16 years ago
media	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
memstick	…
message	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
mfd	mfd: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
misc	Merge branch 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6	16 years ago
mmc	proc tty: switch sdio_uart to ->proc_fops	16 years ago
mtd	Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm	16 years ago
net	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6	16 years ago
nubus	…
of	…
oprofile	oprofile: Thou shalt not call __exit functions from __init functions	16 years ago
parisc	parisc: sba_iommu: fix build bug when CONFIG_PARISC_AGP=y	16 years ago
parport	…
pci	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6	16 years ago
pcmcia	Merge branch 'origin' into devel	16 years ago
platform	Merge branch 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6	16 years ago
pnp	…
power	ds2760_battery.c: fix division by zero	16 years ago
ps3	…
rapidio	rapidio: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
regulator	…
rtc	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
s390	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
sbus	sbus: Auto-load openprom module when device opened.	16 years ago
scsi	proc 2/2: remove struct proc_dir_entry::owner	16 years ago
serial	proc tty: switch serial_core to ->proc_fops	16 years ago
sh	maple: fix Error in kernel-doc notation	16 years ago
sn	…
spi	Merge commit 'origin/master' into next	16 years ago
ssb	b43: Add BCM4307 PCI-ID	16 years ago
staging	Merge branch 'topic/snd_card_new-err' into for-linus	16 years ago
tc	tc: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
telephony	…
thermal	…
uio	UIO: Take offset into account when determining number of pages that can be mapped	16 years ago
usb	proc tty: switch usb-serial to ->proc_fops	16 years ago
uwb	…
video	mm: page_mkwrite change prototype to match fault	16 years ago
virtio	virtio: more neatening of virtio_ring macros.	16 years ago
w1	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6 into devel	16 years ago
watchdog	Merge branch 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6	16 years ago
xen	PM: Rework handling of interrupts during suspend-resume	16 years ago
zorro	zorro: struct device - replace bus_id with dev_name(), dev_set_name()	16 years ago
Kconfig	…
Makefile	ide/net: flip the order of SATA and network init	16 years ago