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scoutfs: support newer ->iterate readdir

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The modern upstream kernel has a ->iterate() readdir file_operattions
method which takes a context and calls dir_emit().   We add some
kernelcompat helpers to juggle the various function definitions, types,
and arguments to support both the old ->readdir(filldir) and the new
->iterate(ctx) interfaces.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2019-11-08 14:30:32 -08:00
committed by Zach Brown
parent 2a6d209854
commit ddd1a4ef5a
3 changed files with 98 additions and 30 deletions
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29
kmod/src/Makefile.kernelcompat
View File

@@ -5,3 +5,32 @@
#
ccflags-y += -include $(src)/kernelcompat.h
#
# v3.10-rc6-21-gbb6f619b3a49
#
# _readdir changes from fop->readdir() to fop->iterate() and from
# filldir(dirent) to dir_emit(ctx).
#
ifneq (,$(shell grep 'iterate.*dir_context' include/linux/fs.h))
ccflags-y += -DKC_ITERATE_DIR_CONTEXT
endif
#
# v3.10-rc6-23-g5f99f4e79abc
#
# Helpers including dir_emit_dots() are added in the process of
# switching dcache_readdir() from fop->readdir() to fop->iterate()
#
ifneq (,$(shell grep 'dir_emit_dots' include/linux/fs.h))
ccflags-y += -DKC_DIR_EMIT_DOTS
endif
#
# RHEL extended the fop struct so to use it we have to set
# a flag to indicate that the struct is large enough and
# contains the pointer.
#
ifneq (,$(shell grep 'FMODE_KABI_ITERATE' include/linux/fs.h))
ccflags-y += -DKC_FMODE_KABI_ITERATE
endif

54
kmod/src/dir.c
View File

@@ -436,28 +436,6 @@ out:
return d_splice_alias(inode, dentry);
}
/* this exists upstream so we can just delete it in a forward port */
static int dir_emit_dots(struct file *file, void *dirent, filldir_t filldir)
{
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = dentry->d_inode;
struct inode *parent = dentry->d_parent->d_inode;
if (file->f_pos == 0) {
if (filldir(dirent, ".", 1, 1, scoutfs_ino(inode), DT_DIR))
return 0;
file->f_pos = 1;
}
if (file->f_pos == 1) {
if (filldir(dirent, "..", 2, 1, scoutfs_ino(parent), DT_DIR))
return 0;
file->f_pos = 2;
}
return 1;
}
/*
* readdir simply iterates over the dirent items for the dir inode and
* uses their offset as the readdir position.
@@ -465,7 +443,8 @@ static int dir_emit_dots(struct file *file, void *dirent, filldir_t filldir)
* It will need to be careful not to read past the region of the dirent
* hash offset keys that it has access to.
*/
static int scoutfs_readdir(struct file *file, void *dirent, filldir_t filldir)
static int KC_DECLARE_READDIR(scoutfs_readdir, struct file *file,
void *dirent, kc_readdir_ctx_t ctx)
{
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
@@ -478,7 +457,7 @@ static int scoutfs_readdir(struct file *file, void *dirent, filldir_t filldir)
u64 pos;
int ret;
if (!dir_emit_dots(file, dirent, filldir))
if (!kc_dir_emit_dots(file, dirent, ctx))
return 0;
dent = alloc_dirent(SCOUTFS_NAME_LEN);
@@ -497,7 +476,7 @@ static int scoutfs_readdir(struct file *file, void *dirent, filldir_t filldir)
for (;;) {
init_dirent_key(&key, SCOUTFS_READDIR_TYPE, scoutfs_ino(inode),
file->f_pos, 0);
kc_readdir_pos(file, ctx), 0);
ret = scoutfs_item_next(sb, &key, &last_key, &val, dir_lock);
if (ret < 0) {
@@ -511,21 +490,24 @@ static int scoutfs_readdir(struct file *file, void *dirent, filldir_t filldir)
scoutfs_corruption(sb, SC_DIRENT_READDIR_NAME_LEN,
corrupt_dirent_readdir_name_len,
"dir_ino %llu pos %llu key "SK_FMT" len %d",
scoutfs_ino(inode), file->f_pos,
scoutfs_ino(inode),
kc_readdir_pos(file, ctx),
SK_ARG(&key), name_len);
ret = -EIO;
goto out;
}
pos = le64_to_cpu(key.skd_major);
kc_readdir_pos(file, ctx) = pos;
if (filldir(dirent, dent->name, name_len, pos,
le64_to_cpu(dent->ino), dentry_type(dent->type))) {
if (!kc_dir_emit(ctx, dent, dent->name, name_len, pos,
le64_to_cpu(dent->ino),
dentry_type(dent->type))) {
ret = 0;
break;
}
file->f_pos = pos + 1;
kc_readdir_pos(file, ctx) = pos + 1;
}
out:
@@ -1737,8 +1719,20 @@ out_unlock:
return ret;
}
#ifdef KC_FMODE_KABI_ITERATE
/* we only need this to set the iterate flag for kabi :/ */
static int scoutfs_dir_open(struct inode *inode, struct file *file)
{
file->f_mode |= FMODE_KABI_ITERATE;
return 0;
}
#endif
const struct file_operations scoutfs_dir_fops = {
.readdir = scoutfs_readdir,
.KC_FOP_READDIR = scoutfs_readdir,
#ifdef KC_FMODE_KABI_ITERATE
.open = scoutfs_dir_open,
#endif
.unlocked_ioctl = scoutfs_ioctl,
.fsync = scoutfs_file_fsync,
.llseek = generic_file_llseek,

45
kmod/src/kernelcompat.h
View File

@@ -1,4 +1,49 @@
#ifndef _SCOUTFS_KERNELCOMPAT_H_
#define _SCOUTFS_KERNELCOMPAT_H_
#ifndef KC_ITERATE_DIR_CONTEXT
#include <linux/fs.h>
typedef filldir_t kc_readdir_ctx_t;
#define KC_DECLARE_READDIR(name, file, dirent, ctx) name(file, dirent, ctx)
#define KC_FOP_READDIR readdir
#define kc_readdir_pos(filp, ctx) (filp)->f_pos
#define kc_dir_emit_dots(file, dirent, ctx) dir_emit_dots(file, dirent, ctx)
#define kc_dir_emit(ctx, dentry, name, name_len, pos, ino, dt) \
(ctx(dentry, name, name_len, pos, ino, dt) == 0)
#else
typedef struct dir_context * kc_readdir_ctx_t;
#define KC_DECLARE_READDIR(name, file, dirent, ctx) name(file, ctx)
#define KC_FOP_READDIR iterate
#define kc_readdir_pos(filp, ctx) (ctx)->pos
#define kc_dir_emit_dots(file, dirent, ctx) dir_emit_dots(file, ctx)
#define kc_dir_emit(ctx, dentry, name, name_len, pos, ino, dt) \
dir_emit(ctx, name, name_len, ino, dt)
#endif
#ifndef KC_DIR_EMIT_DOTS
/*
* Kernels before ->iterate and don't have dir_emit_dots so we give them
* one that works with the ->readdir() filldir() method.
*/
static inline int dir_emit_dots(struct file *file, void *dirent,
filldir_t filldir)
{
if (file->f_pos == 0) {
if (filldir(dirent, ".", 1, 1,
file->f_path.dentry->d_inode->i_ino, DT_DIR))
return 0;
file->f_pos = 1;
}
if (file->f_pos == 1) {
if (filldir(dirent, "..", 2, 1,
parent_ino(file->f_path.dentry), DT_DIR))
return 0;
file->f_pos = 2;
}
return 1;
}
#endif
#endif