From: Shida Zhang <zhangshida@xxxxxxxxxx> 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 <adilger@xxxxxxxxx> Signed-off-by: Shida Zhang <zhangshida@xxxxxxxxxx> Link: https://lore.kernel.org/lkml/A9ECDF14-95A1-4B1E-A815-4B6ABF4916C6@xxxxxxxxx/ --- 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
