From: Shida Zhang <[email protected]>
Following Andreas' suggestion, it is time to adapt these helpers
to handle larger records during runtime, especially in preparation
for the eventual support of ext4 with a block size greater than
PAGE_SIZE.
Suggested-by: Andreas Dilger <[email protected]>
Signed-off-by: Shida Zhang <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]/
---
fs/ext4/ext4.h | 34 ++++++++++++++++++----------------
1 file changed, 18 insertions(+), 16 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0a2d55faa095..87cdf4d56da1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2386,39 +2386,41 @@ static inline unsigned int ext4_dir_rec_len(__u8 name_len,
}
/*
- * If we ever get support for fs block sizes > page_size, we'll need
- * to remove the #if statements in the next two functions...
+ * The next two helpers facilitate the conversion between the encoded
+ * and plain forms of rec_len. Try to access rec_len through these helpers
+ * rather than accessing it directly.
*/
-static inline unsigned int
-ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize)
+static inline
+unsigned int ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize)
{
unsigned len = le16_to_cpu(dlen);
-#if (PAGE_SIZE >= 65536)
+ if (blocksize < 65536)
+ return len;
+
if (len == EXT4_MAX_REC_LEN || len == 0)
return blocksize;
+
return (len & 65532) | ((len & 3) << 16);
-#else
- return len;
-#endif
}
static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)
{
- BUG_ON((len > blocksize) || (blocksize > (1 << 18)) || (len & 3));
-#if (PAGE_SIZE >= 65536)
- if (len < 65536)
+ BUG_ON(len > blocksize);
+ BUG_ON(blocksize > (1 << 18));
+ BUG_ON(len & 3);
+
+ if (len < 65536) /* always true for blocksize < 65536 */
return cpu_to_le16(len);
+
if (len == blocksize) {
if (blocksize == 65536)
return cpu_to_le16(EXT4_MAX_REC_LEN);
- else
- return cpu_to_le16(0);
+
+ return cpu_to_le16(0);
}
+
return cpu_to_le16((len & 65532) | ((len >> 16) & 3));
-#else
- return cpu_to_le16(len);
-#endif
}
/*
--
2.27.0