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Implement loopcxt_check_conflict() 

Add a function that searches for a possible conflicting (i. e. overlaying loop
device).

Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>
This commit is contained in:
Stanislav Brabec 2016-07-14 15:29:21 +02:00 committed by Karel Zak
parent 74a4705a99
commit 211e1d4609
2 changed files with 58 additions and 0 deletions
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3
include/loopdev.h
View File

@ -188,6 +188,9 @@ extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc,
const char *filename,
uint64_t offset, uint64_t sizelimit,
int flags);
extern int loopcxt_check_conflict(struct loopdev_cxt *lc,
const char *filename,
uint64_t offset, uint64_t sizelimit);
extern int loopcxt_is_used(struct loopdev_cxt *lc,
struct stat *st,

55
lib/loopdev.c
View File

@ -1565,6 +1565,61 @@ int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename,
return rc;
}
/*
* Returns: 0 = conflict, < 0 error, 1 no conflicting device
*/
int loopcxt_check_conflict(struct loopdev_cxt *lc, const char *filename,
uint64_t offset, uint64_t sizelimit)
{
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) {
uint64_t lc_sizelimit, lc_offset;
rc = loopcxt_is_used(lc, hasst ? &st : NULL,
filename, offset, sizelimit, 0);
if (!rc)
continue;
if (rc != 1)
break;
DBG(CXT, ul_debugobj(lc, "found %s backed by %s",
loopcxt_get_device(lc), filename));
rc = loopcxt_get_offset(lc, &lc_offset);
if (rc) {
DBG(CXT, ul_debugobj(lc, "failed to get offset for device %s",
loopcxt_get_device(lc)));
break;
}
rc = loopcxt_get_sizelimit(lc, &lc_sizelimit);
if (rc) {
DBG(CXT, ul_debugobj(lc, "failed to get sizelimit for device %s",
loopcxt_get_device(lc)));
break;
}
if (lc_sizelimit != 0 && offset >= lc_offset + lc_sizelimit)
continue;
if (sizelimit != 0 && offset + sizelimit <= lc_offset)
continue;
DBG(CXT, ul_debugobj(lc, "overlapping loop device %s",
loopcxt_get_device(lc)));
rc = 0;
break;
}
loopcxt_deinit_iterator(lc);
return rc;
}
/*
* Returns allocated string with device name
*/