Btrfs: send, lower mem requirements for processing xattrs
Maximum xattr size can be up to nearly the leaf size. For an fs with a
leaf size larger than the page size, using kmalloc requires allocating
multiple pages that are contiguous, which might not be possible if
there's heavy memory fragmentation. Therefore fallback to vmalloc if
we fail to allocate with kmalloc. Also start with a smaller buffer size,
since xattr values typically are smaller than a page.
Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index b67e12e..7edfc7c 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -986,11 +986,13 @@
int num;
u8 type;
- if (found_key->type == BTRFS_XATTR_ITEM_KEY)
- buf_len = BTRFS_MAX_XATTR_SIZE(root);
- else
- buf_len = PATH_MAX;
-
+ /*
+ * Start with a small buffer (1 page). If later we end up needing more
+ * space, which can happen for xattrs on a fs with a leaf size greater
+ * then the page size, attempt to increase the buffer. Typically xattr
+ * values are small.
+ */
+ buf_len = PATH_MAX;
buf = kmalloc(buf_len, GFP_NOFS);
if (!buf) {
ret = -ENOMEM;
@@ -1017,7 +1019,7 @@
ret = -ENAMETOOLONG;
goto out;
}
- if (name_len + data_len > buf_len) {
+ if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root)) {
ret = -E2BIG;
goto out;
}
@@ -1025,12 +1027,34 @@
/*
* Path too long
*/
- if (name_len + data_len > buf_len) {
+ if (name_len + data_len > PATH_MAX) {
ret = -ENAMETOOLONG;
goto out;
}
}
+ if (name_len + data_len > buf_len) {
+ buf_len = name_len + data_len;
+ if (is_vmalloc_addr(buf)) {
+ vfree(buf);
+ buf = NULL;
+ } else {
+ char *tmp = krealloc(buf, buf_len,
+ GFP_NOFS | __GFP_NOWARN);
+
+ if (!tmp)
+ kfree(buf);
+ buf = tmp;
+ }
+ if (!buf) {
+ buf = vmalloc(buf_len);
+ if (!buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ }
+ }
+
read_extent_buffer(eb, buf, (unsigned long)(di + 1),
name_len + data_len);
@@ -1051,7 +1075,7 @@
}
out:
- kfree(buf);
+ kvfree(buf);
return ret;
}