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lib,loopdev: add missing functions 

- improve loop_info usage (don't call ioctl more than once)
 - add functions to get devno and inode of the backing file
 - add function for compare any file with backing file by devno + inode
   or by filename

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2011-12-20 18:25:04 +01:00
parent 7eac65fcf6
commit 6c224de18b
2 changed files with 178 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/loopdev.h
View File

@ -96,6 +96,7 @@ struct loopdev_cxt {
unsigned int has_info:1; /* .info contains data */
unsigned int extra_check:1; /* unusual stuff for iterator */
unsigned int debug:1; /* debug mode ON/OFF */
unsigned int info_failed:1; /* LOOP_GET_STATUS ioctl failed */
struct sysfs_cxt sysfs; /* pointer to /sys/dev/block/<maj:min>/ */
struct loop_info64 info; /* for GET/SET ioctl */
@ -120,6 +121,7 @@ enum {
*/
extern int is_loopdev(const char *device);
extern int loopdev_is_autoclear(const char *device);
extern char *loopdev_get_backing_file(const char *device);
extern int loopdev_is_used(const char *device, const char *filename,
uint64_t offset, int flags);
@ -161,12 +163,22 @@ int loopcxt_set_encryption(struct loopdev_cxt *lc,
const char *password);
extern char *loopcxt_get_backing_file(struct loopdev_cxt *lc);
extern int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno);
extern int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino);
extern int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset);
extern int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size);
extern int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type);
extern const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc);
extern int loopcxt_is_autoclear(struct loopdev_cxt *lc);
extern int loopcxt_is_readonly(struct loopdev_cxt *lc);
extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc,
const char *filename,
uint64_t offset, int flags);
extern int loopcxt_is_used(struct loopdev_cxt *lc,
struct stat *st,
const char *backing_file,
uint64_t offset,
int flags);
#endif /* UTIL_LINUX_LOOPDEV_H */

207
lib/loopdev.c
View File

@ -88,6 +88,7 @@ int loopcxt_set_device(struct loopdev_cxt *lc, const char *device)
lc->fd = -1;
lc->mode = 0;
lc->has_info = 0;
lc->info_failed = 0;
*lc->device = '\0';
memset(&lc->info, 0, sizeof(lc->info));
@ -236,7 +237,6 @@ struct sysfs_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc)
}
}
DBG(lc, loopdev_debug("sysfs: returns context"));
return &lc->sysfs;
}
@ -540,20 +540,23 @@ struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc)
{
int fd;
if (!lc)
if (!lc || lc->info_failed)
return NULL;
if (lc->has_info)
return &lc->info;
DBG(lc, loopdev_debug("reading loop_info64"));
fd = loopcxt_get_fd(lc);
if (fd < 0)
return NULL;
if (ioctl(fd, LOOP_GET_STATUS64, &lc->info) == 0) {
lc->has_info = 1;
lc->info_failed = 0;
DBG(lc, loopdev_debug("reading loop_info64 OK"));
return &lc->info;
} else {
lc->info_failed = 1;
DBG(lc, loopdev_debug("reading loop_info64 FAILED"));
}
return NULL;
@ -587,7 +590,7 @@ char *loopcxt_get_backing_file(struct loopdev_cxt *lc)
}
}
DBG(lc, loopdev_debug("return backing file: %s", res));
DBG(lc, loopdev_debug("get_backing_file [%s]", res));
return res;
}
@ -610,10 +613,11 @@ int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset)
if (lo) {
if (offset)
*offset = lo->lo_offset;
return 0;
rc = 0;
}
}
DBG(lc, loopdev_debug("get_offset [rc=%d]", rc));
return rc;
}
@ -636,10 +640,92 @@ int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size)
if (lo) {
if (size)
*size = lo->lo_sizelimit;
return 0;
rc = 0;
}
}
DBG(lc, loopdev_debug("get_sizelimit [rc=%d]", rc));
return rc;
}
/*
* @lc: context
* @devno: returns encryption type
*
* Cryptoloop is DEPRECATED!
*
* Returns: <0 on error, 0 on success
*/
int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type)
{
struct loop_info64 *lo = loopcxt_get_info(lc);
int rc = -EINVAL;
if (lo) {
if (type)
*type = lo->lo_encrypt_type;
rc = 0;
}
DBG(lc, loopdev_debug("get_encrypt_type [rc=%d]", rc));
return rc;
}
/*
* @lc: context
* @devno: returns crypt name
*
* Cryptoloop is DEPRECATED!
*
* Returns: <0 on error, 0 on success
*/
const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc)
{
struct loop_info64 *lo = loopcxt_get_info(lc);
if (lo)
return (char *) lo->lo_crypt_name;
DBG(lc, loopdev_debug("get_crypt_name failed"));
return NULL;
}
/*
* @lc: context
* @devno: returns backing file devno
*
* Returns: <0 on error, 0 on success
*/
int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno)
{
struct loop_info64 *lo = loopcxt_get_info(lc);
int rc = -EINVAL;
if (lo) {
if (devno)
*devno = lo->lo_device;
rc = 0;
}
DBG(lc, loopdev_debug("get_backing_devno [rc=%d]", rc));
return rc;
}
/*
* @lc: context
* @ino: returns backing file inode
*
* Returns: <0 on error, 0 on success
*/
int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino)
{
struct loop_info64 *lo = loopcxt_get_info(lc);
int rc = -EINVAL;
if (lo) {
if (ino)
*ino = lo->lo_inode;
rc = 0;
}
DBG(lc, loopdev_debug("get_backing_inode [rc=%d]", rc));
return rc;
}
@ -689,6 +775,67 @@ int loopcxt_is_readonly(struct loopdev_cxt *lc)
return 0;
}
/*
* @lc: context
* @st: backing file stat or NULL
* @backing_file: filename
* @offset: offset
* @flags: LOOPDEV_FL_OFFSET if @offset should not be ignored
*
* Returns 1 if the current @lc loopdev is associated with the given backing
* file. Note that the preferred way is to use devno and inode number rather
* than filename. The @backing_file filename is poor solution usable in case
* that you don't have rights to call stat().
*
* Don't forget that old kernels provide very restricted (in size) backing
* filename by LOOP_GET_STAT64 ioctl only.
*/
int loopcxt_is_used(struct loopdev_cxt *lc,
struct stat *st,
const char *backing_file,
uint64_t offset,
int flags)
{
ino_t ino;
dev_t dev;
if (!lc)
return 0;
DBG(lc, loopdev_debug("checking %s vs. %s",
loopcxt_get_device(lc),
backing_file));
if (st && loopcxt_get_backing_inode(lc, &ino) == 0 &&
loopcxt_get_backing_devno(lc, &dev) == 0) {
if (ino == st->st_ino && dev == st->st_dev)
goto found;
/* don't use filename if we have devno and inode */
return 0;
}
/* poor man's solution */
if (backing_file) {
char *name = loopcxt_get_backing_file(lc);
int rc = name && strcmp(name, backing_file) == 0;
free(name);
if (rc)
goto found;
}
return 0;
found:
if (flags & LOOPDEV_FL_OFFSET) {
uint64_t off;
return loopcxt_get_offset(lc, &off) == 0 && off == offset;
}
return 1;
}
/*
* The setting is removed by loopcxt_set_device() loopcxt_next()!
*/
@ -891,6 +1038,7 @@ int loopcxt_setup_device(struct loopdev_cxt *lc)
}
memset(&lc->info, 0, sizeof(lc->info));
lc->has_info = 0;
lc->info_failed = 0;
DBG(lc, loopdev_debug("setup success [rc=0]"));
return 0;
@ -998,7 +1146,7 @@ int loopdev_is_used(const char *device, const char *filename,
uint64_t offset, int flags)
{
struct loopdev_cxt lc;
char *backing = NULL;
struct stat st;
int rc = 0;
if (!device)
@ -1007,23 +1155,10 @@ int loopdev_is_used(const char *device, const char *filename,
loopcxt_init(&lc, 0);
loopcxt_set_device(&lc, device);
backing = loopcxt_get_backing_file(&lc);
if (!backing)
goto done;
if (filename && strcmp(filename, backing) != 0)
goto done;
if (flags & LOOPDEV_FL_OFFSET) {
uint64_t off;
rc = !stat(filename, &st);
rc = loopcxt_is_used(&lc, rc ? &st : NULL, filename, offset, flags);
if (loopcxt_get_offset(&lc, &off) != 0 || off != offset)
goto done;
}
rc = 1;
done:
free(backing);
loopcxt_deinit(&lc);
return rc;
}
@ -1046,33 +1181,23 @@ int loopdev_delete(const char *device)
int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename,
uint64_t offset, int flags)
{
int rc;
int rc, hasst;
struct stat st;
if (!filename)
return -EINVAL;
hasst = !stat(filename, &st);
rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED);
if (rc)
return rc;
while((rc = loopcxt_next(lc)) == 0) {
char *backing = loopcxt_get_backing_file(lc);
while ((rc = loopcxt_next(lc)) == 0) {
if (!backing || strcmp(backing, filename)) {
free(backing);
continue;
}
free(backing);
if (flags & LOOPDEV_FL_OFFSET) {
uint64_t off;
if (loopcxt_get_offset(lc, &off) != 0 || offset != off)
continue;
}
rc = 0;
break;
if (loopcxt_is_used(lc, hasst ? &st : NULL,
filename, offset, flags))
break;
}
loopcxt_deinit_iterator(lc);