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authorDavid Howells <dhowells@redhat.com>2020-04-26 10:12:27 +0100
committerDavid Howells <dhowells@redhat.com>2020-06-04 15:37:57 +0100
commit6ef350b1842081bef7e4879993f47f052b7007e7 (patch)
treed681b177ad5b69d75b28b7c8f40619491cdaf86b /fs/afs
parent8a070a964877c71139cba46202f6f263c2b9419d (diff)
downloadlinux-6ef350b1842081bef7e4879993f47f052b7007e7.tar.bz2
afs: Detect cell aliases 2 - Cells with no root volumes
Implement the second phase of cell alias detection. This part handles alias detection for cells that don't have root.cell volumes and so we have to find some other volume or fileserver to query. We take the first volume from each such cell and attempt to look it up in the new cell. If found, we compare the records, if they are the same, we judge the cell names to be aliases. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs')
-rw-r--r--fs/afs/vl_alias.c90
1 files changed, 89 insertions, 1 deletions
diff --git a/fs/afs/vl_alias.c b/fs/afs/vl_alias.c
index d1d91a25fbe0..76bfa4dde4a4 100644
--- a/fs/afs/vl_alias.c
+++ b/fs/afs/vl_alias.c
@@ -180,6 +180,94 @@ is_alias:
return 1;
}
+/*
+ * Query the new cell for a volume from a cell we're already using.
+ */
+static int afs_query_for_alias_one(struct afs_cell *cell, struct key *key,
+ struct afs_cell *p)
+{
+ struct afs_volume *volume, *pvol = NULL;
+ int ret;
+
+ /* Arbitrarily pick the first volume in the list. */
+ read_lock(&p->proc_lock);
+ if (!list_empty(&p->proc_volumes))
+ pvol = afs_get_volume(list_first_entry(&p->proc_volumes,
+ struct afs_volume, proc_link));
+ read_unlock(&p->proc_lock);
+ if (!pvol)
+ return 0;
+
+ _enter("%s:%s", cell->name, pvol->name);
+
+ /* And see if it's in the new cell. */
+ volume = afs_sample_volume(cell, key, pvol->name, pvol->name_len);
+ if (IS_ERR(volume)) {
+ afs_put_volume(cell->net, pvol);
+ if (PTR_ERR(volume) != -ENOMEDIUM)
+ return PTR_ERR(volume);
+ /* That volume is not in the new cell, so not an alias */
+ return 0;
+ }
+
+ /* The new cell has a like-named volume also - compare volume ID,
+ * server and address lists.
+ */
+ ret = 0;
+ if (pvol->vid == volume->vid) {
+ rcu_read_lock();
+ if (afs_compare_volume_slists(volume, pvol))
+ ret = 1;
+ rcu_read_unlock();
+ }
+
+ afs_put_volume(cell->net, volume);
+ afs_put_volume(cell->net, pvol);
+ return ret;
+}
+
+/*
+ * Query the new cell for volumes we know exist in cells we're already using.
+ */
+static int afs_query_for_alias(struct afs_cell *cell, struct key *key)
+{
+ struct afs_cell *p;
+
+ _enter("%s", cell->name);
+
+ if (mutex_lock_interruptible(&cell->net->proc_cells_lock) < 0)
+ return -ERESTARTSYS;
+
+ hlist_for_each_entry(p, &cell->net->proc_cells, proc_link) {
+ if (p == cell || p->alias_of)
+ continue;
+ if (list_empty(&p->proc_volumes))
+ continue;
+ if (p->root_volume)
+ continue; /* Ignore cells that have a root.cell volume. */
+ afs_get_cell(p);
+ mutex_unlock(&cell->net->proc_cells_lock);
+
+ if (afs_query_for_alias_one(cell, key, p) != 0)
+ goto is_alias;
+
+ if (mutex_lock_interruptible(&cell->net->proc_cells_lock) < 0) {
+ afs_put_cell(cell->net, p);
+ return -ERESTARTSYS;
+ }
+
+ afs_put_cell(cell->net, p);
+ }
+
+ mutex_unlock(&cell->net->proc_cells_lock);
+ _leave(" = 0");
+ return 0;
+
+is_alias:
+ cell->alias_of = p; /* Transfer our ref */
+ return 1;
+}
+
static int afs_do_cell_detect_alias(struct afs_cell *cell, struct key *key)
{
struct afs_volume *root_volume;
@@ -199,7 +287,7 @@ static int afs_do_cell_detect_alias(struct afs_cell *cell, struct key *key)
/* Okay, this cell doesn't have an root.cell volume. We need to
* locate some other random volume and use that to check.
*/
- return -ENOMEDIUM;
+ return afs_query_for_alias(cell, key);
}
/*