[PATCH 4/6] fuse2fs: enable caching IO manager

Darrick J. Wong
2025-09-16T01:07:53Z

Enable the new dynamic iocache I/O manager in the fuse server, and turn
off all the other cache control.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
fuse4fs/Makefile.in | 3 +-
fuse4fs/fuse4fs.1.in | 6 ----
fuse4fs/fuse4fs.c | 71 +++----------------------------------------------
misc/Makefile.in | 4 ++-
misc/fuse2fs.1.in | 6 ----
misc/fuse2fs.c | 73 ++++----------------------------------------------
6 files changed, 15 insertions(+), 148 deletions(-)

diff --git a/fuse4fs/Makefile.in b/fuse4fs/Makefile.in
index 9f3547c271638f..0a558da23ced81 100644
--- a/fuse4fs/Makefile.in
+++ b/fuse4fs/Makefile.in
@@ -147,7 +147,8 @@ fuse4fs.o: $(srcdir)/fuse4fs.c $(top_builddir)/lib/config.h \
$(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/ext2fsP.h \
$(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/version.h \
$(top_srcdir)/lib/e2p/e2p.h $(top_srcdir)/lib/support/cache.h \
- $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h \
+ $(top_srcdir)/lib/support/iocache.h
journal.o: $(srcdir)/../debugfs/journal.c $(top_builddir)/lib/config.h \
$(top_builddir)/lib/dirpaths.h $(srcdir)/../debugfs/journal.h \
$(top_srcdir)/e2fsck/jfs_user.h $(top_srcdir)/e2fsck/e2fsck.h \
diff --git a/fuse4fs/fuse4fs.1.in b/fuse4fs/fuse4fs.1.in
index 119cbcc903d8af..7ab197465c9713 100644
--- a/fuse4fs/fuse4fs.1.in
+++ b/fuse4fs/fuse4fs.1.in
@@ -48,12 +48,6 @@ .SS "fuse4fs options:"
\fB-o\fR acl
enable file access control lists
.TP
-\fB-o\fR cache_size
-Set the disk cache size to this quantity.
-The quantity may contain the suffixes k, m, or g.
-By default, the size is 32MB.
-The size may not be larger than 2GB.
-.TP
\fB-o\fR direct
Use O_DIRECT to access the block device.
.TP
diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c
index c4397fc365ced7..2dd7c0f6759de5 100644
--- a/fuse4fs/fuse4fs.c
+++ b/fuse4fs/fuse4fs.c
@@ -53,6 +53,7 @@
#include "ext2fs/ext2fsP.h"
#include "support/list.h"
#include "support/cache.h"
+#include "support/iocache.h"

#include "../version.h"
#include "uuid/uuid.h"
@@ -290,7 +291,6 @@ struct fuse4fs {
unsigned int blockmask;
unsigned long offset;
unsigned int next_generation;
- unsigned long long cache_size;
char *lockfile;
#ifdef HAVE_CLOCK_MONOTONIC
struct timespec lock_start_time;
@@ -1289,7 +1289,8 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)

dbg_printf(ff, "opening with flags=0x%x\n", flags);

- err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
+ iocache_set_backing_manager(unix_io_manager);
+ err = ext2fs_open2(ff->device, options, flags, 0, 0, iocache_io_manager,
&ff->fs);
if (err == EPERM) {
err_printf(ff, "%s.\n",
@@ -1298,7 +1299,7 @@ static errcode_t fuse4fs_open(struct fuse4fs *ff, int libext2_flags)
ff->ro = 1;
ff->norecovery = 1;
err = ext2fs_open2(ff->device, options, flags, 0, 0,
- unix_io_manager, &ff->fs);
+ iocache_io_manager, &ff->fs);
}
if (err) {
err_printf(ff, "%s.\n", error_message(err));
@@ -1321,25 +1322,6 @@ static inline bool fuse4fs_on_bdev(const struct fuse4fs *ff)
return ff->fs->io->flags & CHANNEL_FLAGS_BLOCK_DEVICE;
}

-static errcode_t fuse4fs_config_cache(struct fuse4fs *ff)
-{
- char buf[128];
- errcode_t err;
-
- snprintf(buf, sizeof(buf), "cache_blocks=%llu",
- FUSE4FS_B_TO_FSBT(ff, ff->cache_size));
- err = io_channel_set_options(ff->fs->io, buf);
- if (err) {
- err_printf(ff, "%s %lluk: %s\n",
- _("cannot set disk cache size to"),
- ff->cache_size >> 10,
- error_message(err));
- return err;
- }
-
- return 0;
-}
-
static errcode_t fuse4fs_check_support(struct fuse4fs *ff)
{
ext2_filsys fs = ff->fs;
@@ -7193,7 +7175,6 @@ enum {
FUSE4FS_VERSION,
FUSE4FS_HELP,
FUSE4FS_HELPFULL,
- FUSE4FS_CACHE_SIZE,
FUSE4FS_DIRSYNC,
FUSE4FS_ERRORS_BEHAVIOR,
#ifdef HAVE_FUSE_IOMAP
@@ -7243,7 +7224,6 @@ static struct fuse_opt fuse4fs_opts[] = {
FUSE_OPT_KEY("user_xattr", FUSE4FS_IGNORED),
FUSE_OPT_KEY("noblock_validity", FUSE4FS_IGNORED),
FUSE_OPT_KEY("nodelalloc", FUSE4FS_IGNORED),
- FUSE_OPT_KEY("cache_size=%s", FUSE4FS_CACHE_SIZE),
FUSE_OPT_KEY("dirsync", FUSE4FS_DIRSYNC),
FUSE_OPT_KEY("errors=%s", FUSE4FS_ERRORS_BEHAVIOR),
#ifdef HAVE_FUSE_IOMAP
@@ -7282,16 +7262,6 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
return 0;
}
return 1;
- case FUSE4FS_CACHE_SIZE:
- ff->cache_size = parse_num_blocks2(arg + 11, -1);
- if (ff->cache_size < 1 || ff->cache_size > INT32_MAX) {
- fprintf(stderr, "%s: %s\n", arg,
- _("cache size must be between 1 block and 2GB."));
- return -1;
- }
-
- /* do not pass through to libfuse */
- return 0;
case FUSE4FS_ERRORS_BEHAVIOR:
if (strcmp(arg + 7, "continue") == 0)
ff->errors_behavior = EXT2_ERRORS_CONTINUE;
@@ -7348,7 +7318,6 @@ static int fuse4fs_opt_proc(void *data, const char *arg,
" -o kernel run this as if it were the kernel, which sets:\n"
" allow_others,default_permissions,suid,dev\n"
" -o directio use O_DIRECT to read and write the disk\n"
- " -o cache_size=N[KMG] use a disk cache of this size\n"
" -o errors= behavior when an error is encountered:\n"
" continue|remount-ro|panic\n"
#ifdef HAVE_FUSE_IOMAP
@@ -7391,28 +7360,6 @@ static const char *get_subtype(const char *argv0)
return "ext4";
}

-/* Figure out a reasonable default size for the disk cache */
-static unsigned long long default_cache_size(void)
-{
- long pages = 0, pagesize = 0;
- unsigned long long max_cache;
- unsigned long long ret = 32ULL << 20; /* 32 MB */
-
-#ifdef _SC_PHYS_PAGES
- pages = sysconf(_SC_PHYS_PAGES);
-#endif
-#ifdef _SC_PAGESIZE
- pagesize = sysconf(_SC_PAGESIZE);
-#endif
- if (pages > 0 && pagesize > 0) {
- max_cache = (unsigned long long)pagesize * pages / 20;
-
- if (max_cache > 0 && ret > max_cache)
- ret = max_cache;
- }
- return ret;
-}
-
#ifdef HAVE_FUSE_IOMAP
static inline bool fuse4fs_discover_iomap(struct fuse4fs *ff)
{
@@ -7687,16 +7634,6 @@ int main(int argc, char *argv[])
fctx.translate_inums = 0;
}

- if (!fctx.cache_size)
- fctx.cache_size = default_cache_size();
- if (fctx.cache_size) {
- err = fuse4fs_config_cache(&fctx);
- if (err) {
- ret = 32;
- goto out;
- }
- }
-
err = fuse4fs_check_support(&fctx);
if (err) {
ret = 32;
diff --git a/misc/Makefile.in b/misc/Makefile.in
index ec964688acd623..8a3adc70fb736e 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -880,7 +880,9 @@ fuse2fs.o: $(srcdir)/fuse2fs.c $(top_builddir)/lib/config.h \
$(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/hashmap.h \
$(top_srcdir)/lib/ext2fs/bitops.h $(top_srcdir)/lib/ext2fs/ext2fsP.h \
$(top_srcdir)/lib/ext2fs/ext2fs.h $(top_srcdir)/version.h \
- $(top_srcdir)/lib/e2p/e2p.h
+ $(top_srcdir)/lib/e2p/e2p.h $(top_srcdir)/lib/support/cache.h \
+ $(top_srcdir)/lib/support/list.h $(top_srcdir)/lib/support/xbitops.h \
+ $(top_srcdir)/lib/support/iocache.h
e2fuzz.o: $(srcdir)/e2fuzz.c $(top_builddir)/lib/config.h \
$(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
$(top_builddir)/lib/ext2fs/ext2_types.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
diff --git a/misc/fuse2fs.1.in b/misc/fuse2fs.1.in
index 0c0934f03c9543..21917bdda31a12 100644
--- a/misc/fuse2fs.1.in
+++ b/misc/fuse2fs.1.in
@@ -48,12 +48,6 @@ .SS "fuse2fs options:"
\fB-o\fR acl
enable file access control lists
.TP
-\fB-o\fR cache_size
-Set the disk cache size to this quantity.
-The quantity may contain the suffixes k, m, or g.
-By default, the size is 32MB.
-The size may not be larger than 2GB.
-.TP
\fB-o\fR direct
Use O_DIRECT to access the block device.
.TP
diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 5e4680ca023282..8bd7cedc9f1ca8 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -50,6 +50,9 @@
#include "ext2fs/ext2fs.h"
#include "ext2fs/ext2_fs.h"
#include "ext2fs/ext2fsP.h"
+#include "support/list.h"
+#include "support/cache.h"
+#include "support/iocache.h"

#include "../version.h"
#include "uuid/uuid.h"
@@ -283,7 +286,6 @@ struct fuse2fs {
unsigned int blockmask;
unsigned long offset;
unsigned int next_generation;
- unsigned long long cache_size;
char *lockfile;
#ifdef HAVE_CLOCK_MONOTONIC
struct timespec lock_start_time;
@@ -1119,7 +1121,8 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)

dbg_printf(ff, "opening with flags=0x%x\n", flags);

- err = ext2fs_open2(ff->device, options, flags, 0, 0, unix_io_manager,
+ iocache_set_backing_manager(unix_io_manager);
+ err = ext2fs_open2(ff->device, options, flags, 0, 0, iocache_io_manager,
&ff->fs);
if (err == EPERM) {
err_printf(ff, "%s.\n",
@@ -1128,7 +1131,7 @@ static errcode_t fuse2fs_open(struct fuse2fs *ff, int libext2_flags)
ff->ro = 1;
ff->norecovery = 1;
err = ext2fs_open2(ff->device, options, flags, 0, 0,
- unix_io_manager, &ff->fs);
+ iocache_io_manager, &ff->fs);
}
if (err) {
err_printf(ff, "%s.\n", error_message(err));
@@ -1147,25 +1150,6 @@ static inline bool fuse2fs_on_bdev(const struct fuse2fs *ff)
return ff->fs->io->flags & CHANNEL_FLAGS_BLOCK_DEVICE;
}

-static errcode_t fuse2fs_config_cache(struct fuse2fs *ff)
-{
- char buf[128];
- errcode_t err;
-
- snprintf(buf, sizeof(buf), "cache_blocks=%llu",
- FUSE2FS_B_TO_FSBT(ff, ff->cache_size));
- err = io_channel_set_options(ff->fs->io, buf);
- if (err) {
- err_printf(ff, "%s %lluk: %s\n",
- _("cannot set disk cache size to"),
- ff->cache_size >> 10,
- error_message(err));
- return err;
- }
-
- return 0;
-}
-
static errcode_t fuse2fs_check_support(struct fuse2fs *ff)
{
ext2_filsys fs = ff->fs;
@@ -6750,7 +6734,6 @@ enum {
FUSE2FS_VERSION,
FUSE2FS_HELP,
FUSE2FS_HELPFULL,
- FUSE2FS_CACHE_SIZE,
FUSE2FS_DIRSYNC,
FUSE2FS_ERRORS_BEHAVIOR,
#ifdef HAVE_FUSE_IOMAP
@@ -6800,7 +6783,6 @@ static struct fuse_opt fuse2fs_opts[] = {
FUSE_OPT_KEY("user_xattr", FUSE2FS_IGNORED),
FUSE_OPT_KEY("noblock_validity", FUSE2FS_IGNORED),
FUSE_OPT_KEY("nodelalloc", FUSE2FS_IGNORED),
- FUSE_OPT_KEY("cache_size=%s", FUSE2FS_CACHE_SIZE),
FUSE_OPT_KEY("dirsync", FUSE2FS_DIRSYNC),
FUSE_OPT_KEY("errors=%s", FUSE2FS_ERRORS_BEHAVIOR),
#ifdef HAVE_FUSE_IOMAP
@@ -6839,16 +6821,6 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
return 0;
}
return 1;
- case FUSE2FS_CACHE_SIZE:
- ff->cache_size = parse_num_blocks2(arg + 11, -1);
- if (ff->cache_size < 1 || ff->cache_size > INT32_MAX) {
- fprintf(stderr, "%s: %s\n", arg,
- _("cache size must be between 1 block and 2GB."));
- return -1;
- }
-
- /* do not pass through to libfuse */
- return 0;
case FUSE2FS_ERRORS_BEHAVIOR:
if (strcmp(arg + 7, "continue") == 0)
ff->errors_behavior = EXT2_ERRORS_CONTINUE;
@@ -6905,7 +6877,6 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
" -o kernel run this as if it were the kernel, which sets:\n"
" allow_others,default_permissions,suid,dev\n"
" -o directio use O_DIRECT to read and write the disk\n"
- " -o cache_size=N[KMG] use a disk cache of this size\n"
" -o errors= behavior when an error is encountered:\n"
" continue|remount-ro|panic\n"
#ifdef HAVE_FUSE_IOMAP
@@ -6949,28 +6920,6 @@ static const char *get_subtype(const char *argv0)
return "ext4";
}

-/* Figure out a reasonable default size for the disk cache */
-static unsigned long long default_cache_size(void)
-{
- long pages = 0, pagesize = 0;
- unsigned long long max_cache;
- unsigned long long ret = 32ULL << 20; /* 32 MB */
-
-#ifdef _SC_PHYS_PAGES
- pages = sysconf(_SC_PHYS_PAGES);
-#endif
-#ifdef _SC_PAGESIZE
- pagesize = sysconf(_SC_PAGESIZE);
-#endif
- if (pages > 0 && pagesize > 0) {
- max_cache = (unsigned long long)pagesize * pages / 20;
-
- if (max_cache > 0 && ret > max_cache)
- ret = max_cache;
- }
- return ret;
-}
-
#ifdef HAVE_FUSE_IOMAP
static inline bool fuse2fs_discover_iomap(struct fuse2fs *ff)
{
@@ -7130,16 +7079,6 @@ int main(int argc, char *argv[])
goto out;
}

- if (!fctx.cache_size)
- fctx.cache_size = default_cache_size();
- if (fctx.cache_size) {
- err = fuse2fs_config_cache(&fctx);
- if (err) {
- ret = 32;
- goto out;
- }
- }
-
err = fuse2fs_check_support(&fctx);
if (err) {
ret = 32;