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afs: Detect cell aliases 3 - YFS Cells with a canonical cell name op

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YFS Volume Location servers have an operation by which the cell name may be
queried.  Use this to find out what a YFS server thinks the canonical cell
name should be.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2020-04-27 15:01:09 +01:00
parent 6ef350b184
commit 6dfdf5369c
2 changed files with 62 additions and 0 deletions
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58
fs/afs/vl_alias.c
View File

@ -268,12 +268,70 @@ static int afs_query_for_alias(struct afs_cell *cell, struct key *key)
return 1;
}
/*
* Look up a VLDB record for a volume.
*/
static char *afs_vl_get_cell_name(struct afs_cell *cell, struct key *key)
{
struct afs_vl_cursor vc;
char *cell_name = ERR_PTR(-EDESTADDRREQ);
bool skipped = false, not_skipped = false;
int ret;
if (!afs_begin_vlserver_operation(&vc, cell, key))
return ERR_PTR(-ERESTARTSYS);
while (afs_select_vlserver(&vc)) {
if (!test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags)) {
vc.ac.error = -EOPNOTSUPP;
skipped = true;
continue;
}
not_skipped = true;
cell_name = afs_yfsvl_get_cell_name(&vc);
}
ret = afs_end_vlserver_operation(&vc);
if (skipped && !not_skipped)
ret = -EOPNOTSUPP;
return ret < 0 ? ERR_PTR(ret) : cell_name;
}
static int yfs_check_canonical_cell_name(struct afs_cell *cell, struct key *key)
{
struct afs_cell *master;
char *cell_name;
cell_name = afs_vl_get_cell_name(cell, key);
if (IS_ERR(cell_name))
return PTR_ERR(cell_name);
if (strcmp(cell_name, cell->name) == 0) {
kfree(cell_name);
return 0;
}
master = afs_lookup_cell(cell->net, cell_name, strlen(cell_name),
NULL, false);
kfree(cell_name);
if (IS_ERR(master))
return PTR_ERR(master);
cell->alias_of = master; /* Transfer our ref */
return 1;
}
static int afs_do_cell_detect_alias(struct afs_cell *cell, struct key *key)
{
struct afs_volume *root_volume;
int ret;
_enter("%s", cell->name);
ret = yfs_check_canonical_cell_name(cell, key);
if (ret != -EOPNOTSUPP)
return ret;
/* Try and get the root.cell volume for comparison with other cells */
root_volume = afs_sample_volume(cell, key, "root.cell", 9);
if (!IS_ERR(root_volume)) {

4
fs/afs/vl_rotate.c
View File

@ -151,6 +151,10 @@ bool afs_select_vlserver(struct afs_vl_cursor *vc)
vc->error = error;
vc->flags |= AFS_VL_CURSOR_RETRY;
goto next_server;
case -EOPNOTSUPP:
_debug("notsupp");
goto next_server;
}
restart_from_beginning: