[PATCH v3 14/17] btrfs: create and free extent fscrypt_infos

[Sweet Tea Dorminy <sweettea-kernel@dorminy.me>]

Each extent_map will end up with a pointer to its associated
fscrypt_info if any, which should have the same lifetime as the
extent_map. Add creation of fscrypt_infos for new extent_maps, and
freeing as appropriate.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 fs/btrfs/extent_map.c | 18 ++++++++++++++++++
 fs/btrfs/extent_map.h |  1 +
 fs/btrfs/fscrypt.c    | 13 +++++++++++++
 fs/btrfs/fscrypt.h    |  4 ++++
 fs/btrfs/inode.c      |  6 ++++++
 5 files changed, 42 insertions(+)

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 0cdb3e86f29b..cb4b7517b253 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -9,6 +9,7 @@
 #include "extent_map.h"
 #include "compression.h"
 #include "btrfs_inode.h"
+#include "fscrypt.h"
 
 
 static struct kmem_cache *extent_map_cache;
@@ -65,6 +66,8 @@ void free_extent_map(struct extent_map *em)
 	if (!em)
 		return;
 	if (refcount_dec_and_test(&em->refs)) {
+		if (em->fscrypt_info)
+			fscrypt_free_extent_info(&em->fscrypt_info);
 		WARN_ON(extent_map_in_tree(em));
 		WARN_ON(!list_empty(&em->list));
 		if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
@@ -207,6 +210,12 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
 	if (!list_empty(&prev->list) || !list_empty(&next->list))
 		return 0;
 
+	/*
+	 * Don't merge adjacent encrypted maps.
+	 */
+	if (prev->fscrypt_info || next->fscrypt_info)
+		return 0;
+
 	ASSERT(next->block_start != EXTENT_MAP_DELALLOC &&
 	       prev->block_start != EXTENT_MAP_DELALLOC);
 
@@ -817,6 +826,8 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end,
 			split->generation = gen;
 			split->flags = flags;
 			split->compress_type = em->compress_type;
+			btrfs_fscrypt_copy_fscrypt_info(inode, em->fscrypt_info,
+							&split->fscrypt_info);
 			replace_extent_mapping(em_tree, em, split, modified);
 			free_extent_map(split);
 			split = split2;
@@ -858,6 +869,8 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end,
 				split->orig_block_len = 0;
 			}
 
+			btrfs_fscrypt_copy_fscrypt_info(inode, em->fscrypt_info,
+							&split->fscrypt_info);
 			if (extent_map_in_tree(em)) {
 				replace_extent_mapping(em_tree, em, split,
 						       modified);
@@ -1019,6 +1032,8 @@ int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
 	split_pre->flags = flags;
 	split_pre->compress_type = em->compress_type;
 	split_pre->generation = em->generation;
+	btrfs_fscrypt_copy_fscrypt_info(inode, em->fscrypt_info,
+					&split_pre->fscrypt_info);
 
 	replace_extent_mapping(em_tree, em, split_pre, 1);
 
@@ -1038,6 +1053,9 @@ int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
 	split_mid->flags = flags;
 	split_mid->compress_type = em->compress_type;
 	split_mid->generation = em->generation;
+	btrfs_fscrypt_copy_fscrypt_info(inode, em->fscrypt_info,
+					&split_mid->fscrypt_info);
+
 	add_extent_mapping(em_tree, split_mid, 1);
 
 	/* Once for us */
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 35d27c756e08..3ffb74412d31 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -50,6 +50,7 @@ struct extent_map {
 	 */
 	u64 generation;
 	unsigned long flags;
+	struct fscrypt_info *fscrypt_info;
 	/* Used for chunk mappings, flag EXTENT_FLAG_FS_MAPPING must be set */
 	struct map_lookup *map_lookup;
 	refcount_t refs;
diff --git a/fs/btrfs/fscrypt.c b/fs/btrfs/fscrypt.c
index 499073376110..5508cbc6bccb 100644
--- a/fs/btrfs/fscrypt.c
+++ b/fs/btrfs/fscrypt.c
@@ -215,6 +215,19 @@ static struct block_device **btrfs_fscrypt_get_devices(struct super_block *sb,
 	return devs;
 }
 
+void btrfs_fscrypt_copy_fscrypt_info(struct btrfs_inode *inode,
+				     struct fscrypt_info *from,
+				     struct fscrypt_info **to_ptr)
+{
+	if (from == NULL) {
+		*to_ptr = NULL;
+		return;
+	}
+
+	fscrypt_get_extent_info_ref(from);
+	*to_ptr = from;
+}
+
 const struct fscrypt_operations btrfs_fscrypt_ops = {
 	.get_context = btrfs_fscrypt_get_context,
 	.set_context = btrfs_fscrypt_set_context,
diff --git a/fs/btrfs/fscrypt.h b/fs/btrfs/fscrypt.h
index c08fd52c99b4..a489bb54b3b1 100644
--- a/fs/btrfs/fscrypt.h
+++ b/fs/btrfs/fscrypt.h
@@ -37,6 +37,10 @@ static inline bool btrfs_fscrypt_match_name(struct fscrypt_name *fname,
 }
 #endif /* CONFIG_FS_ENCRYPTION */
 
+void btrfs_fscrypt_copy_fscrypt_info(struct btrfs_inode *inode,
+				     struct fscrypt_info *from,
+				     struct fscrypt_info **to_ptr);
+
 extern const struct fscrypt_operations btrfs_fscrypt_ops;
 
 #endif /* BTRFS_FSCRYPT_H */
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 053c7170ce6e..7726957284c1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7319,6 +7319,12 @@ static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
 		em->compress_type = compress_type;
 	}
 
+	ret = fscrypt_prepare_new_extent(&inode->vfs_inode, &em->fscrypt_info);
+	if (ret < 0) {
+		free_extent_map(em);
+		return ERR_PTR(ret);
+	}
+
 	ret = btrfs_replace_extent_map_range(inode, em, true);
 	if (ret) {
 		free_extent_map(em);
-- 
2.41.0