thr3ads.net - Virtualization - [PATCH 6/9] virtio_balloon: remove the balloon-kvm file system [Mar 2021]

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Christoph Hellwig

2021-Mar-09 15:53 UTC

make alloc_anon_inode more useful

Hi all,

this series first renames the existing alloc_anon_inode to
alloc_anon_inode_sb to clearly mark it as requiring a superblock.

It then adds a new alloc_anon_inode that works on the anon_inode
file system super block, thus removing tons of boilerplate code.

The few remainig callers of alloc_anon_inode_sb all use alloc_file_pseudo
later, but might also be ripe for some cleanup.

Diffstat:
 arch/powerpc/platforms/pseries/cmm.c |   27 +-------------
 drivers/dma-buf/dma-buf.c            |    2 -
 drivers/gpu/drm/drm_drv.c            |   64 +----------------------------------
 drivers/misc/cxl/api.c               |    2 -
 drivers/misc/vmw_balloon.c           |   24 +------------
 drivers/scsi/cxlflash/ocxl_hw.c      |    2 -
 drivers/virtio/virtio_balloon.c      |   30 +---------------
 fs/aio.c                             |    2 -
 fs/anon_inodes.c                     |   15 +++++++-
 fs/libfs.c                           |    2 -
 include/linux/anon_inodes.h          |    1 
 include/linux/fs.h                   |    2 -
 kernel/resource.c                    |   30 ++--------------
 mm/z3fold.c                          |   38 +-------------------
 mm/zsmalloc.c                        |   48 +-------------------------
 15 files changed, 39 insertions(+), 250 deletions(-)

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 1/9] fs: rename alloc_anon_inode to alloc_anon_inode_sb

Rename alloc_inode to free the name for a new variant that does not
need boilerplate to create a super_block first.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 arch/powerpc/platforms/pseries/cmm.c | 2 +-
 drivers/dma-buf/dma-buf.c            | 2 +-
 drivers/gpu/drm/drm_drv.c            | 2 +-
 drivers/misc/cxl/api.c               | 2 +-
 drivers/misc/vmw_balloon.c           | 2 +-
 drivers/scsi/cxlflash/ocxl_hw.c      | 2 +-
 drivers/virtio/virtio_balloon.c      | 2 +-
 fs/aio.c                             | 2 +-
 fs/anon_inodes.c                     | 4 ++--
 fs/libfs.c                           | 2 +-
 include/linux/fs.h                   | 2 +-
 kernel/resource.c                    | 2 +-
 mm/z3fold.c                          | 2 +-
 mm/zsmalloc.c                        | 2 +-
 14 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c
b/arch/powerpc/platforms/pseries/cmm.c
index 45a3a3022a85c9..6d36b858b14df1 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -580,7 +580,7 @@ static int cmm_balloon_compaction_init(void)
 		return rc;
 	}
 
-	b_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
+	b_dev_info.inode = alloc_anon_inode_sb(balloon_mnt->mnt_sb);
 	if (IS_ERR(b_dev_info.inode)) {
 		rc = PTR_ERR(b_dev_info.inode);
 		b_dev_info.inode = NULL;
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f264b70c383eb4..dedcc9483352dc 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -445,7 +445,7 @@ static inline int is_dma_buf_file(struct file *file)
 static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
 {
 	struct file *file;
-	struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
+	struct inode *inode = alloc_anon_inode_sb(dma_buf_mnt->mnt_sb);
 
 	if (IS_ERR(inode))
 		return ERR_CAST(inode);
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 20d22e41d7ce74..87e7214a8e3565 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -519,7 +519,7 @@ static struct inode *drm_fs_inode_new(void)
 		return ERR_PTR(r);
 	}
 
-	inode = alloc_anon_inode(drm_fs_mnt->mnt_sb);
+	inode = alloc_anon_inode_sb(drm_fs_mnt->mnt_sb);
 	if (IS_ERR(inode))
 		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
 
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index b493de962153ba..2efbf6c98028ef 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -73,7 +73,7 @@ static struct file *cxl_getfile(const char *name,
 		goto err_module;
 	}
 
-	inode = alloc_anon_inode(cxl_vfs_mount->mnt_sb);
+	inode = alloc_anon_inode_sb(cxl_vfs_mount->mnt_sb);
 	if (IS_ERR(inode)) {
 		file = ERR_CAST(inode);
 		goto err_fs;
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index b837e7eba5f7dc..5d057a05ddbee8 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -1900,7 +1900,7 @@ static __init int vmballoon_compaction_init(struct
vmballoon *b)
 		return PTR_ERR(vmballoon_mnt);
 
 	b->b_dev_info.migratepage = vmballoon_migratepage;
-	b->b_dev_info.inode = alloc_anon_inode(vmballoon_mnt->mnt_sb);
+	b->b_dev_info.inode = alloc_anon_inode_sb(vmballoon_mnt->mnt_sb);
 
 	if (IS_ERR(b->b_dev_info.inode))
 		return PTR_ERR(b->b_dev_info.inode);
diff --git a/drivers/scsi/cxlflash/ocxl_hw.c b/drivers/scsi/cxlflash/ocxl_hw.c
index 244fc27215dc79..40184ed926b557 100644
--- a/drivers/scsi/cxlflash/ocxl_hw.c
+++ b/drivers/scsi/cxlflash/ocxl_hw.c
@@ -88,7 +88,7 @@ static struct file *ocxlflash_getfile(struct device *dev,
const char *name,
 		goto err2;
 	}
 
-	inode = alloc_anon_inode(ocxlflash_vfs_mount->mnt_sb);
+	inode = alloc_anon_inode_sb(ocxlflash_vfs_mount->mnt_sb);
 	if (IS_ERR(inode)) {
 		rc = PTR_ERR(inode);
 		dev_err(dev, "%s: alloc_anon_inode failed rc=%d\n",
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 8985fc2cea8615..cae76ee5bdd688 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -916,7 +916,7 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	}
 
 	vb->vb_dev_info.migratepage = virtballoon_migratepage;
-	vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
+	vb->vb_dev_info.inode = alloc_anon_inode_sb(balloon_mnt->mnt_sb);
 	if (IS_ERR(vb->vb_dev_info.inode)) {
 		err = PTR_ERR(vb->vb_dev_info.inode);
 		goto out_kern_unmount;
diff --git a/fs/aio.c b/fs/aio.c
index 1f32da13d39ee6..d1c2aa7fd6de7c 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -234,7 +234,7 @@ static const struct address_space_operations aio_ctx_aops;
 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
 {
 	struct file *file;
-	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
+	struct inode *inode = alloc_anon_inode_sb(aio_mnt->mnt_sb);
 	if (IS_ERR(inode))
 		return ERR_CAST(inode);
 
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index a280156138ed89..4745fc37014332 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -63,7 +63,7 @@ static struct inode *anon_inode_make_secure_inode(
 	const struct qstr qname = QSTR_INIT(name, strlen(name));
 	int error;
 
-	inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
+	inode = alloc_anon_inode_sb(anon_inode_mnt->mnt_sb);
 	if (IS_ERR(inode))
 		return inode;
 	inode->i_flags &= ~S_PRIVATE;
@@ -231,7 +231,7 @@ static int __init anon_inode_init(void)
 	if (IS_ERR(anon_inode_mnt))
 		panic("anon_inode_init() kernel mount failed (%ld)\n",
PTR_ERR(anon_inode_mnt));
 
-	anon_inode_inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
+	anon_inode_inode = alloc_anon_inode_sb(anon_inode_mnt->mnt_sb);
 	if (IS_ERR(anon_inode_inode))
 		panic("anon_inode_init() inode allocation failed (%ld)\n",
PTR_ERR(anon_inode_inode));
 
diff --git a/fs/libfs.c b/fs/libfs.c
index e2de5401abca5a..600bebc1cd847f 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1216,7 +1216,7 @@ static int anon_set_page_dirty(struct page *page)
 	return 0;
 };
 
-struct inode *alloc_anon_inode(struct super_block *s)
+struct inode *alloc_anon_inode_sb(struct super_block *s)
 {
 	static const struct address_space_operations anon_aops = {
 		.set_page_dirty = anon_set_page_dirty,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ec8f3ddf4a6aa8..52387368af3c00 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3286,7 +3286,7 @@ extern int simple_write_end(struct file *file, struct
address_space *mapping,
 			loff_t pos, unsigned len, unsigned copied,
 			struct page *page, void *fsdata);
 extern int always_delete_dentry(const struct dentry *);
-extern struct inode *alloc_anon_inode(struct super_block *);
+extern struct inode *alloc_anon_inode_sb(struct super_block *);
 extern int simple_nosetlease(struct file *, long, struct file_lock **, void
**);
 extern const struct dentry_operations simple_dentry_operations;
 
diff --git a/kernel/resource.c b/kernel/resource.c
index 627e61b0c12418..0fd091a3f2fc66 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1863,7 +1863,7 @@ static int __init iomem_init_inode(void)
 		return rc;
 	}
 
-	inode = alloc_anon_inode(iomem_vfs_mount->mnt_sb);
+	inode = alloc_anon_inode_sb(iomem_vfs_mount->mnt_sb);
 	if (IS_ERR(inode)) {
 		rc = PTR_ERR(inode);
 		pr_err("Cannot allocate inode for iomem: %d\n", rc);
diff --git a/mm/z3fold.c b/mm/z3fold.c
index b5dafa7e44e429..e7cd9298b221f5 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -376,7 +376,7 @@ static void z3fold_unmount(void)
 static const struct address_space_operations z3fold_aops;
 static int z3fold_register_migration(struct z3fold_pool *pool)
 {
-	pool->inode = alloc_anon_inode(z3fold_mnt->mnt_sb);
+	pool->inode = alloc_anon_inode_sb(z3fold_mnt->mnt_sb);
 	if (IS_ERR(pool->inode)) {
 		pool->inode = NULL;
 		return 1;
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 30c358b7202510..a6449a2ad861de 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2086,7 +2086,7 @@ static const struct address_space_operations zsmalloc_aops
= {
 
 static int zs_register_migration(struct zs_pool *pool)
 {
-	pool->inode = alloc_anon_inode(zsmalloc_mnt->mnt_sb);
+	pool->inode = alloc_anon_inode_sb(zsmalloc_mnt->mnt_sb);
 	if (IS_ERR(pool->inode)) {
 		pool->inode = NULL;
 		return 1;
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 2/9] fs: add an argument-less alloc_anon_inode

Add a new alloc_anon_inode helper that allocates an inode on
the anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 fs/anon_inodes.c            | 15 +++++++++++++--
 include/linux/anon_inodes.h |  1 +
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 4745fc37014332..b6a8ea71920bc3 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -63,7 +63,7 @@ static struct inode *anon_inode_make_secure_inode(
 	const struct qstr qname = QSTR_INIT(name, strlen(name));
 	int error;
 
-	inode = alloc_anon_inode_sb(anon_inode_mnt->mnt_sb);
+	inode = alloc_anon_inode();
 	if (IS_ERR(inode))
 		return inode;
 	inode->i_flags &= ~S_PRIVATE;
@@ -225,13 +225,24 @@ int anon_inode_getfd_secure(const char *name, const struct
file_operations *fops
 }
 EXPORT_SYMBOL_GPL(anon_inode_getfd_secure);
 
+/**
+ * alloc_anon_inode - create a new anonymous inode
+ *
+ * Create an inode on the anon_inode file system and return it.
+ */
+struct inode *alloc_anon_inode(void)
+{
+	return alloc_anon_inode_sb(anon_inode_mnt->mnt_sb);
+}
+EXPORT_SYMBOL_GPL(alloc_anon_inode);
+
 static int __init anon_inode_init(void)
 {
 	anon_inode_mnt = kern_mount(&anon_inode_fs_type);
 	if (IS_ERR(anon_inode_mnt))
 		panic("anon_inode_init() kernel mount failed (%ld)\n",
PTR_ERR(anon_inode_mnt));
 
-	anon_inode_inode = alloc_anon_inode_sb(anon_inode_mnt->mnt_sb);
+	anon_inode_inode = alloc_anon_inode();
 	if (IS_ERR(anon_inode_inode))
 		panic("anon_inode_init() inode allocation failed (%ld)\n",
PTR_ERR(anon_inode_inode));
 
diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h
index 71881a2b6f7860..b5ae9a6eda9923 100644
--- a/include/linux/anon_inodes.h
+++ b/include/linux/anon_inodes.h
@@ -21,6 +21,7 @@ int anon_inode_getfd_secure(const char *name,
 			    const struct file_operations *fops,
 			    void *priv, int flags,
 			    const struct inode *context_inode);
+struct inode *alloc_anon_inode(void);
 
 #endif /* _LINUX_ANON_INODES_H */
 
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 3/9] powerpc/pseries: remove the ppc-cmm file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 arch/powerpc/platforms/pseries/cmm.c | 27 ++-------------------------
 1 file changed, 2 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c
b/arch/powerpc/platforms/pseries/cmm.c
index 6d36b858b14df1..9d07e6bea7126c 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -6,6 +6,7 @@
  * Author(s): Brian King (brking at linux.vnet.ibm.com),
  */
 
+#include <linux/anon_inodes.h>
 #include <linux/ctype.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
@@ -502,19 +503,6 @@ static struct notifier_block cmm_mem_nb = {
 };
 
 #ifdef CONFIG_BALLOON_COMPACTION
-static struct vfsmount *balloon_mnt;
-
-static int cmm_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, PPC_CMM_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type balloon_fs = {
-	.name = "ppc-cmm",
-	.init_fs_context = cmm_init_fs_context,
-	.kill_sb = kill_anon_super,
-};
-
 static int cmm_migratepage(struct balloon_dev_info *b_dev_info,
 			   struct page *newpage, struct page *page,
 			   enum migrate_mode mode)
@@ -573,19 +561,10 @@ static int cmm_balloon_compaction_init(void)
 	balloon_devinfo_init(&b_dev_info);
 	b_dev_info.migratepage = cmm_migratepage;
 
-	balloon_mnt = kern_mount(&balloon_fs);
-	if (IS_ERR(balloon_mnt)) {
-		rc = PTR_ERR(balloon_mnt);
-		balloon_mnt = NULL;
-		return rc;
-	}
-
-	b_dev_info.inode = alloc_anon_inode_sb(balloon_mnt->mnt_sb);
+	b_dev_info.inode = alloc_anon_inode();
 	if (IS_ERR(b_dev_info.inode)) {
 		rc = PTR_ERR(b_dev_info.inode);
 		b_dev_info.inode = NULL;
-		kern_unmount(balloon_mnt);
-		balloon_mnt = NULL;
 		return rc;
 	}
 
@@ -597,8 +576,6 @@ static void cmm_balloon_compaction_deinit(void)
 	if (b_dev_info.inode)
 		iput(b_dev_info.inode);
 	b_dev_info.inode = NULL;
-	kern_unmount(balloon_mnt);
-	balloon_mnt = NULL;
 }
 #else /* CONFIG_BALLOON_COMPACTION */
 static int cmm_balloon_compaction_init(void)
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 4/9] drm: remove the drm file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/gpu/drm/drm_drv.c | 64 ++-------------------------------------
 1 file changed, 3 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 87e7214a8e3565..af293d76f979e5 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -26,6 +26,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/anon_inodes.h>
 #include <linux/debugfs.h>
 #include <linux/fs.h>
 #include <linux/module.h>
@@ -475,65 +476,6 @@ void drm_dev_unplug(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_dev_unplug);
 
-/*
- * DRM internal mount
- * We want to be able to allocate our own "struct address_space" to
control
- * memory-mappings in VRAM (or stolen RAM, ...). However, core MM does not
allow
- * stand-alone address_space objects, so we need an underlying inode. As there
- * is no way to allocate an independent inode easily, we need a fake internal
- * VFS mount-point.
- *
- * The drm_fs_inode_new() function allocates a new inode, drm_fs_inode_free()
- * frees it again. You are allowed to use iget() and iput() to get references
to
- * the inode. But each drm_fs_inode_new() call must be paired with exactly one
- * drm_fs_inode_free() call (which does not have to be the last iput()).
- * We use drm_fs_inode_*() to manage our internal VFS mount-point and share it
- * between multiple inode-users. You could, technically, call
- * iget() + drm_fs_inode_free() directly after alloc and sometime later do an
- * iput(), but this way you'd end up with a new vfsmount for each inode.
- */
-
-static int drm_fs_cnt;
-static struct vfsmount *drm_fs_mnt;
-
-static int drm_fs_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, 0x010203ff) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type drm_fs_type = {
-	.name		= "drm",
-	.owner		= THIS_MODULE,
-	.init_fs_context = drm_fs_init_fs_context,
-	.kill_sb	= kill_anon_super,
-};
-
-static struct inode *drm_fs_inode_new(void)
-{
-	struct inode *inode;
-	int r;
-
-	r = simple_pin_fs(&drm_fs_type, &drm_fs_mnt, &drm_fs_cnt);
-	if (r < 0) {
-		DRM_ERROR("Cannot mount pseudo fs: %d\n", r);
-		return ERR_PTR(r);
-	}
-
-	inode = alloc_anon_inode_sb(drm_fs_mnt->mnt_sb);
-	if (IS_ERR(inode))
-		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
-
-	return inode;
-}
-
-static void drm_fs_inode_free(struct inode *inode)
-{
-	if (inode) {
-		iput(inode);
-		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
-	}
-}
-
 /**
  * DOC: component helper usage recommendations
  *
@@ -563,7 +505,7 @@ static void drm_dev_init_release(struct drm_device *dev,
void *res)
 {
 	drm_legacy_ctxbitmap_cleanup(dev);
 	drm_legacy_remove_map_hash(dev);
-	drm_fs_inode_free(dev->anon_inode);
+	iput(dev->anon_inode);
 
 	put_device(dev->dev);
 	/* Prevent use-after-free in drm_managed_release when debugging is
@@ -616,7 +558,7 @@ static int drm_dev_init(struct drm_device *dev,
 	if (ret)
 		return ret;
 
-	dev->anon_inode = drm_fs_inode_new();
+	dev->anon_inode = alloc_anon_inode();
 	if (IS_ERR(dev->anon_inode)) {
 		ret = PTR_ERR(dev->anon_inode);
 		DRM_ERROR("Cannot allocate anonymous inode: %d\n", ret);
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 5/9] vmw_balloon: remove the balloon-vmware file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/misc/vmw_balloon.c | 24 ++----------------------
 1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 5d057a05ddbee8..be4be32f858253 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -16,6 +16,7 @@
 //#define DEBUG
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/anon_inodes.h>
 #include <linux/types.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -1735,20 +1736,6 @@ static inline void vmballoon_debugfs_exit(struct
vmballoon *b)
 
 
 #ifdef CONFIG_BALLOON_COMPACTION
-
-static int vmballoon_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, BALLOON_VMW_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type vmballoon_fs = {
-	.name           	= "balloon-vmware",
-	.init_fs_context	= vmballoon_init_fs_context,
-	.kill_sb        	= kill_anon_super,
-};
-
-static struct vfsmount *vmballoon_mnt;
-
 /**
  * vmballoon_migratepage() - migrates a balloon page.
  * @b_dev_info: balloon device information descriptor.
@@ -1878,8 +1865,6 @@ static void vmballoon_compaction_deinit(struct vmballoon
*b)
 		iput(b->b_dev_info.inode);
 
 	b->b_dev_info.inode = NULL;
-	kern_unmount(vmballoon_mnt);
-	vmballoon_mnt = NULL;
 }
 
 /**
@@ -1895,13 +1880,8 @@ static void vmballoon_compaction_deinit(struct vmballoon
*b)
  */
 static __init int vmballoon_compaction_init(struct vmballoon *b)
 {
-	vmballoon_mnt = kern_mount(&vmballoon_fs);
-	if (IS_ERR(vmballoon_mnt))
-		return PTR_ERR(vmballoon_mnt);
-
 	b->b_dev_info.migratepage = vmballoon_migratepage;
-	b->b_dev_info.inode = alloc_anon_inode_sb(vmballoon_mnt->mnt_sb);
-
+	b->b_dev_info.inode = alloc_anon_inode();
 	if (IS_ERR(b->b_dev_info.inode))
 		return PTR_ERR(b->b_dev_info.inode);
 
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 6/9] virtio_balloon: remove the balloon-kvm file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/virtio/virtio_balloon.c | 30 +++---------------------------
 1 file changed, 3 insertions(+), 27 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index cae76ee5bdd688..1efb890cd3ff09 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -6,6 +6,7 @@
  *  Copyright 2008 Rusty Russell IBM Corporation
  */
 
+#include <linux/anon_inodes.h>
 #include <linux/virtio.h>
 #include <linux/virtio_balloon.h>
 #include <linux/swap.h>
@@ -42,10 +43,6 @@
 	(1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT))
 #define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 <<
VIRTIO_BALLOON_HINT_BLOCK_ORDER)
 
-#ifdef CONFIG_BALLOON_COMPACTION
-static struct vfsmount *balloon_mnt;
-#endif
-
 enum virtio_balloon_vq {
 	VIRTIO_BALLOON_VQ_INFLATE,
 	VIRTIO_BALLOON_VQ_DEFLATE,
@@ -805,18 +802,6 @@ static int virtballoon_migratepage(struct balloon_dev_info
*vb_dev_info,
 
 	return MIGRATEPAGE_SUCCESS;
 }
-
-static int balloon_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, BALLOON_KVM_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type balloon_fs = {
-	.name           = "balloon-kvm",
-	.init_fs_context = balloon_init_fs_context,
-	.kill_sb        = kill_anon_super,
-};
-
 #endif /* CONFIG_BALLOON_COMPACTION */
 
 static unsigned long shrink_free_pages(struct virtio_balloon *vb,
@@ -909,17 +894,11 @@ static int virtballoon_probe(struct virtio_device *vdev)
 		goto out_free_vb;
 
 #ifdef CONFIG_BALLOON_COMPACTION
-	balloon_mnt = kern_mount(&balloon_fs);
-	if (IS_ERR(balloon_mnt)) {
-		err = PTR_ERR(balloon_mnt);
-		goto out_del_vqs;
-	}
-
 	vb->vb_dev_info.migratepage = virtballoon_migratepage;
-	vb->vb_dev_info.inode = alloc_anon_inode_sb(balloon_mnt->mnt_sb);
+	vb->vb_dev_info.inode = alloc_anon_inode();
 	if (IS_ERR(vb->vb_dev_info.inode)) {
 		err = PTR_ERR(vb->vb_dev_info.inode);
-		goto out_kern_unmount;
+		goto out_del_vqs;
 	}
 	vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
 #endif
@@ -1016,8 +995,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 out_iput:
 #ifdef CONFIG_BALLOON_COMPACTION
 	iput(vb->vb_dev_info.inode);
-out_kern_unmount:
-	kern_unmount(balloon_mnt);
 out_del_vqs:
 #endif
 	vdev->config->del_vqs(vdev);
@@ -1070,7 +1047,6 @@ static void virtballoon_remove(struct virtio_device *vdev)
 	if (vb->vb_dev_info.inode)
 		iput(vb->vb_dev_info.inode);
 
-	kern_unmount(balloon_mnt);
 #endif
 	kfree(vb);
 }
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 7/9] iomem: remove the iomem file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 kernel/resource.c | 30 ++++--------------------------
 1 file changed, 4 insertions(+), 26 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 0fd091a3f2fc66..12560553c26796 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -26,6 +26,7 @@
 #include <linux/mm.h>
 #include <linux/mount.h>
 #include <linux/resource_ext.h>
+#include <linux/anon_inodes.h>
 #include <uapi/linux/magic.h>
 #include <asm/io.h>
 
@@ -1838,37 +1839,14 @@ static int __init strict_iomem(char *str)
 	return 1;
 }
 
-static int iomem_fs_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, DEVMEM_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type iomem_fs_type = {
-	.name		= "iomem",
-	.owner		= THIS_MODULE,
-	.init_fs_context = iomem_fs_init_fs_context,
-	.kill_sb	= kill_anon_super,
-};
-
 static int __init iomem_init_inode(void)
 {
-	static struct vfsmount *iomem_vfs_mount;
-	static int iomem_fs_cnt;
 	struct inode *inode;
-	int rc;
-
-	rc = simple_pin_fs(&iomem_fs_type, &iomem_vfs_mount,
&iomem_fs_cnt);
-	if (rc < 0) {
-		pr_err("Cannot mount iomem pseudo filesystem: %d\n", rc);
-		return rc;
-	}
 
-	inode = alloc_anon_inode_sb(iomem_vfs_mount->mnt_sb);
+	inode = alloc_anon_inode();
 	if (IS_ERR(inode)) {
-		rc = PTR_ERR(inode);
-		pr_err("Cannot allocate inode for iomem: %d\n", rc);
-		simple_release_fs(&iomem_vfs_mount, &iomem_fs_cnt);
-		return rc;
+		pr_err("Cannot allocate inode for iomem: %zd\n", PTR_ERR(inode));
+		return PTR_ERR(inode);
 	}
 
 	/*
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 8/9] z3fold: remove the z3fold file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 mm/z3fold.c | 38 ++------------------------------------
 1 file changed, 2 insertions(+), 36 deletions(-)

diff --git a/mm/z3fold.c b/mm/z3fold.c
index e7cd9298b221f5..e0749a3d8987de 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -23,6 +23,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/anon_inodes.h>
 #include <linux/atomic.h>
 #include <linux/sched.h>
 #include <linux/cpumask.h>
@@ -345,38 +346,10 @@ static inline void free_handle(unsigned long handle,
struct z3fold_header *zhdr)
 	}
 }
 
-static int z3fold_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, Z3FOLD_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type z3fold_fs = {
-	.name		= "z3fold",
-	.init_fs_context = z3fold_init_fs_context,
-	.kill_sb	= kill_anon_super,
-};
-
-static struct vfsmount *z3fold_mnt;
-static int z3fold_mount(void)
-{
-	int ret = 0;
-
-	z3fold_mnt = kern_mount(&z3fold_fs);
-	if (IS_ERR(z3fold_mnt))
-		ret = PTR_ERR(z3fold_mnt);
-
-	return ret;
-}
-
-static void z3fold_unmount(void)
-{
-	kern_unmount(z3fold_mnt);
-}
-
 static const struct address_space_operations z3fold_aops;
 static int z3fold_register_migration(struct z3fold_pool *pool)
 {
-	pool->inode = alloc_anon_inode_sb(z3fold_mnt->mnt_sb);
+	pool->inode = alloc_anon_inode();
 	if (IS_ERR(pool->inode)) {
 		pool->inode = NULL;
 		return 1;
@@ -1787,22 +1760,15 @@ MODULE_ALIAS("zpool-z3fold");
 
 static int __init init_z3fold(void)
 {
-	int ret;
-
 	/* Make sure the z3fold header is not larger than the page size */
 	BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE);
-	ret = z3fold_mount();
-	if (ret)
-		return ret;
 
 	zpool_register_driver(&z3fold_zpool_driver);
-
 	return 0;
 }
 
 static void __exit exit_z3fold(void)
 {
-	z3fold_unmount();
 	zpool_unregister_driver(&z3fold_zpool_driver);
 }
 
-- 
2.30.1

Christoph Hellwig

2021-Mar-09 15:53 UTC

head link

[PATCH 9/9] zsmalloc: remove the zsmalloc file system

Just use the generic anon_inode file system.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 mm/zsmalloc.c | 48 +++---------------------------------------------
 1 file changed, 3 insertions(+), 45 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index a6449a2ad861de..a7d2f471935447 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -41,6 +41,7 @@
 #include <linux/slab.h>
 #include <linux/pgtable.h>
 #include <asm/tlbflush.h>
+#include <linux/anon_inodes.h>
 #include <linux/cpumask.h>
 #include <linux/cpu.h>
 #include <linux/vmalloc.h>
@@ -176,10 +177,6 @@ struct zs_size_stat {
 static struct dentry *zs_stat_root;
 #endif
 
-#ifdef CONFIG_COMPACTION
-static struct vfsmount *zsmalloc_mnt;
-#endif
-
 /*
  * We assign a page to ZS_ALMOST_EMPTY fullness group when:
  *	n <= N / f, where
@@ -308,8 +305,6 @@ static void kick_deferred_free(struct zs_pool *pool);
 static void init_deferred_free(struct zs_pool *pool);
 static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
 #else
-static int zsmalloc_mount(void) { return 0; }
-static void zsmalloc_unmount(void) {}
 static int zs_register_migration(struct zs_pool *pool) { return 0; }
 static void zs_unregister_migration(struct zs_pool *pool) {}
 static void migrate_lock_init(struct zspage *zspage) {}
@@ -1751,33 +1746,6 @@ static void lock_zspage(struct zspage *zspage)
 	} while ((page = get_next_page(page)) != NULL);
 }
 
-static int zs_init_fs_context(struct fs_context *fc)
-{
-	return init_pseudo(fc, ZSMALLOC_MAGIC) ? 0 : -ENOMEM;
-}
-
-static struct file_system_type zsmalloc_fs = {
-	.name		= "zsmalloc",
-	.init_fs_context = zs_init_fs_context,
-	.kill_sb	= kill_anon_super,
-};
-
-static int zsmalloc_mount(void)
-{
-	int ret = 0;
-
-	zsmalloc_mnt = kern_mount(&zsmalloc_fs);
-	if (IS_ERR(zsmalloc_mnt))
-		ret = PTR_ERR(zsmalloc_mnt);
-
-	return ret;
-}
-
-static void zsmalloc_unmount(void)
-{
-	kern_unmount(zsmalloc_mnt);
-}
-
 static void migrate_lock_init(struct zspage *zspage)
 {
 	rwlock_init(&zspage->lock);
@@ -2086,7 +2054,7 @@ static const struct address_space_operations zsmalloc_aops
= {
 
 static int zs_register_migration(struct zs_pool *pool)
 {
-	pool->inode = alloc_anon_inode_sb(zsmalloc_mnt->mnt_sb);
+	pool->inode = alloc_anon_inode();
 	if (IS_ERR(pool->inode)) {
 		pool->inode = NULL;
 		return 1;
@@ -2506,14 +2474,10 @@ static int __init zs_init(void)
 {
 	int ret;
 
-	ret = zsmalloc_mount();
-	if (ret)
-		goto out;
-
 	ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare",
 				zs_cpu_prepare, zs_cpu_dead);
 	if (ret)
-		goto hp_setup_fail;
+		return ret;
 
 #ifdef CONFIG_ZPOOL
 	zpool_register_driver(&zs_zpool_driver);
@@ -2522,11 +2486,6 @@ static int __init zs_init(void)
 	zs_stat_init();
 
 	return 0;
-
-hp_setup_fail:
-	zsmalloc_unmount();
-out:
-	return ret;
 }
 
 static void __exit zs_exit(void)
@@ -2534,7 +2493,6 @@ static void __exit zs_exit(void)
 #ifdef CONFIG_ZPOOL
 	zpool_unregister_driver(&zs_zpool_driver);
 #endif
-	zsmalloc_unmount();
 	cpuhp_remove_state(CPUHP_MM_ZS_PREPARE);
 
 	zs_stat_exit();
-- 
2.30.1

Matthew Wilcox

2021-Mar-10 04:05 UTC

head link

make alloc_anon_inode more useful

On Tue, Mar 09, 2021 at 04:53:39PM +0100, Christoph Hellwig
wrote:> this series first renames the existing alloc_anon_inode to
> alloc_anon_inode_sb to clearly mark it as requiring a superblock.
> 
> It then adds a new alloc_anon_inode that works on the anon_inode
> file system super block, thus removing tons of boilerplate code.
> 
> The few remainig callers of alloc_anon_inode_sb all use alloc_file_pseudo
> later, but might also be ripe for some cleanup.
On a somewhat related note, could I get you to look at
drivers/video/fbdev/core/fb_defio.c?

As far as I can tell, there's no need for fb_deferred_io_aops to exist.
We could just set file->f_mapping->a_ops to NULL, and set_page_dirty()
would do the exact same thing this code does (except it would get the
return value correct).

But maybe that would make something else go wrong that distinguishes
between page->mapping being NULL and page->mapping->a_ops->foo being
NULL?
Completely untested patch ...

diff --git a/drivers/video/fbdev/core/fb_defio.c
b/drivers/video/fbdev/core/fb_defio.c
index a591d291b231..441ec31d3e4d 100644
--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -151,17 +151,6 @@ static const struct vm_operations_struct
fb_deferred_io_vm_ops = {
 	.page_mkwrite	= fb_deferred_io_mkwrite,
 };
 
-static int fb_deferred_io_set_page_dirty(struct page *page)
-{
-	if (!PageDirty(page))
-		SetPageDirty(page);
-	return 0;
-}
-
-static const struct address_space_operations fb_deferred_io_aops = {
-	.set_page_dirty = fb_deferred_io_set_page_dirty,
-};
-
 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
 {
 	vma->vm_ops = &fb_deferred_io_vm_ops;
@@ -212,14 +201,6 @@ void fb_deferred_io_init(struct fb_info *info)
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
 
-void fb_deferred_io_open(struct fb_info *info,
-			 struct inode *inode,
-			 struct file *file)
-{
-	file->f_mapping->a_ops = &fb_deferred_io_aops;
-}
-EXPORT_SYMBOL_GPL(fb_deferred_io_open);
-
 void fb_deferred_io_cleanup(struct fb_info *info)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 06f5805de2de..c4ba76359f22 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1415,10 +1415,7 @@ __releases(&info->lock)
 		if (res)
 			module_put(info->fbops->owner);
 	}
-#ifdef CONFIG_FB_DEFERRED_IO
-	if (info->fbdefio)
-		fb_deferred_io_open(info, inode, file);
-#endif
+	file->f_mapping->a_ops = NULL;
 out:
 	unlock_fb_info(info);
 	if (res)
diff --git a/include/linux/fb.h b/include/linux/fb.h
index ecfbcc0553a5..a8dccd23c249 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -659,9 +659,6 @@ static inline void __fb_pad_aligned_buffer(u8 *dst, u32
d_pitch,
 /* drivers/video/fb_defio.c */
 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma);
 extern void fb_deferred_io_init(struct fb_info *info);
-extern void fb_deferred_io_open(struct fb_info *info,
-				struct inode *inode,
-				struct file *file);
 extern void fb_deferred_io_cleanup(struct fb_info *info);
 extern int fb_deferred_io_fsync(struct file *file, loff_t start,
 				loff_t end, int datasync);

Jingbo Xu

2023-Feb-03 09:49 UTC

head link

make alloc_anon_inode more useful

Hi,

Sorry for digging...

This patch series seems useful for fs developers.  I'm not sure its
current status and why it doesn't get merged.


On 3/9/21 11:53 PM, Christoph Hellwig wrote:> Hi all,
> 
> this series first renames the existing alloc_anon_inode to
> alloc_anon_inode_sb to clearly mark it as requiring a superblock.
> 
> It then adds a new alloc_anon_inode that works on the anon_inode
> file system super block, thus removing tons of boilerplate code.
> 
> The few remainig callers of alloc_anon_inode_sb all use alloc_file_pseudo
> later, but might also be ripe for some cleanup.
> 
> Diffstat:
>  arch/powerpc/platforms/pseries/cmm.c |   27 +-------------
>  drivers/dma-buf/dma-buf.c            |    2 -
>  drivers/gpu/drm/drm_drv.c            |   64
+----------------------------------
>  drivers/misc/cxl/api.c               |    2 -
>  drivers/misc/vmw_balloon.c           |   24 +------------
>  drivers/scsi/cxlflash/ocxl_hw.c      |    2 -
>  drivers/virtio/virtio_balloon.c      |   30 +---------------
>  fs/aio.c                             |    2 -
>  fs/anon_inodes.c                     |   15 +++++++-
>  fs/libfs.c                           |    2 -
>  include/linux/anon_inodes.h          |    1 
>  include/linux/fs.h                   |    2 -
>  kernel/resource.c                    |   30 ++--------------
>  mm/z3fold.c                          |   38 +-------------------
>  mm/zsmalloc.c                        |   48 +-------------------------
>  15 files changed, 39 insertions(+), 250 deletions(-)
> 
-- 
Thanks,
Jingbo

Virtualization - Mar 2021 - [PATCH 6/9] virtio_balloon: remove the balloon-kvm file system

make alloc_anon_inode more useful

[PATCH 1/9] fs: rename alloc_anon_inode to alloc_anon_inode_sb

[PATCH 2/9] fs: add an argument-less alloc_anon_inode

[PATCH 3/9] powerpc/pseries: remove the ppc-cmm file system

[PATCH 4/9] drm: remove the drm file system

[PATCH 5/9] vmw_balloon: remove the balloon-vmware file system

[PATCH 6/9] virtio_balloon: remove the balloon-kvm file system

[PATCH 7/9] iomem: remove the iomem file system

[PATCH 8/9] z3fold: remove the z3fold file system

[PATCH 9/9] zsmalloc: remove the zsmalloc file system

make alloc_anon_inode more useful

make alloc_anon_inode more useful