On Wed, Oct 24, 2018 at 9:50 AM Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > On Tue, Oct 23, 2018 at 11:19 PM Phillip Potter <phil@xxxxxxxxxxxxxxxx> wrote: > > > > Deduplicate the ext2 file type conversion implementation. > > > > Original patch by Amir Goldstein. > > > > v2: > > - Rebased against Linux 4.19 by Phillip Potter > > - This version does not remove EXT2_FT_x enum from fs/ext2/ext2.h, > > as these values are now used in compile-time checks added by > > Phillip Potter to make sure they remain the same as FT_x values > > > > v1: > > - Initial implementation > > > > Same comments as how to apply a patch and about changelog as patch 1. > Won't repeat for other patches. > > I think it would be also good to mention there is a lurking bug if code > ever tries to access ext2_type_by_mode[S_IFMT] because on-disk > data is corrupted. So my old notes on the alleged ext2 bug: https://marc.info/?l=linux-fsdevel&m=148243866204444&w=2 > > > Signed-off-by: Phillip Potter <phil@xxxxxxxxxxxxxxxx> > > --- > > fs/ext2/dir.c | 51 ++++++++++++++++++++++----------------------------- > > 1 file changed, 22 insertions(+), 29 deletions(-) > > > > diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c > > index 3b8114def693..420d4b9e8980 100644 > > --- a/fs/ext2/dir.c > > +++ b/fs/ext2/dir.c > > @@ -252,33 +252,10 @@ ext2_validate_entry(char *base, unsigned offset, unsigned mask) > > return (char *)p - base; > > } > > > > -static unsigned char ext2_filetype_table[EXT2_FT_MAX] = { > > - [EXT2_FT_UNKNOWN] = DT_UNKNOWN, > > - [EXT2_FT_REG_FILE] = DT_REG, > > - [EXT2_FT_DIR] = DT_DIR, > > - [EXT2_FT_CHRDEV] = DT_CHR, > > - [EXT2_FT_BLKDEV] = DT_BLK, > > - [EXT2_FT_FIFO] = DT_FIFO, > > - [EXT2_FT_SOCK] = DT_SOCK, > > - [EXT2_FT_SYMLINK] = DT_LNK, > > -}; > > - > > -#define S_SHIFT 12 > > -static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = { > > - [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE, > > - [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR, > > - [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV, > > - [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV, > > - [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO, > > - [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK, > > - [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK, > > -}; > > - > > static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) > > { > > - umode_t mode = inode->i_mode; > > if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) > > - de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; > > + de->file_type = fs_umode_to_ftype(inode->i_mode); > > else > > de->file_type = 0; > > } > > @@ -293,14 +270,14 @@ ext2_readdir(struct file *file, struct dir_context *ctx) > > unsigned long n = pos >> PAGE_SHIFT; > > unsigned long npages = dir_pages(inode); > > unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); > > - unsigned char *types = NULL; > > bool need_revalidate = !inode_eq_iversion(inode, file->f_version); > > + bool has_filetype; > > > > if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) > > return 0; > > > > - if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) > > - types = ext2_filetype_table; > > + has_filetype = > > + EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE); > > > > for ( ; n < npages; n++, offset = 0) { > > char *kaddr, *limit; > > @@ -335,8 +312,24 @@ ext2_readdir(struct file *file, struct dir_context *ctx) > > if (de->inode) { > > unsigned char d_type = DT_UNKNOWN; > > > > - if (types && de->file_type < EXT2_FT_MAX) > > - d_type = types[de->file_type]; > > + /* > > + * compile-time asserts that generic FT_x types > > + * still match EXT2_FT_x types - no need to list > > + * for other functions as well as build will > > + * fail either way Please remove the part about "no need to list for other functions..." Imagine how kernel code would look like if every call to BUILD_BUG_ON() would have a comment explaining how BUILD_BUG_ON() works... Thanks, Amir.
