[PATCH] mtd/block2mtd: don't poke into block layer internals
Christoph Hellwig
hch at lst.de
Thu Oct 14 07:52:06 PDT 2021
block2mtd is a bit of a mess as it pokes directly into the block layer
internal page cache. Switch it to use the proper file abstraction
instead. Note that this contains a small behavior change in that erase
now unconditionally writes all Fs instead of first scanning for them.
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
drivers/mtd/devices/block2mtd.c | 203 ++++++++------------------------
1 file changed, 48 insertions(+), 155 deletions(-)
diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index c08721b11642b..ea8ec9956c3e8 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -34,7 +34,7 @@
/* Info for the block device */
struct block2mtd_dev {
struct list_head list;
- struct block_device *blkdev;
+ struct file *file;
struct mtd_info mtd;
struct mutex write_mutex;
};
@@ -43,58 +43,35 @@ struct block2mtd_dev {
/* Static info about the MTD, used in cleanup_module */
static LIST_HEAD(blkmtd_device_list);
-
-static struct page *page_read(struct address_space *mapping, pgoff_t index)
-{
- return read_mapping_page(mapping, index, NULL);
-}
+static u_long allfs[PAGE_SIZE / sizeof(u_long)] = {
+ [0 ... (PAGE_SIZE / sizeof(u_long)) - 1] = -1UL,
+};
/* erase a specified part of the device */
-static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
-{
- struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
- struct page *page;
- pgoff_t index = to >> PAGE_SHIFT; // page index
- int pages = len >> PAGE_SHIFT;
- u_long *p;
- u_long *max;
-
- while (pages) {
- page = page_read(mapping, index);
- if (IS_ERR(page))
- return PTR_ERR(page);
-
- max = page_address(page) + PAGE_SIZE;
- for (p=page_address(page); p<max; p++)
- if (*p != -1UL) {
- lock_page(page);
- memset(page_address(page), 0xff, PAGE_SIZE);
- set_page_dirty(page);
- unlock_page(page);
- balance_dirty_pages_ratelimited(mapping);
- break;
- }
-
- put_page(page);
- pages--;
- index++;
- }
- return 0;
-}
static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
{
struct block2mtd_dev *dev = mtd->priv;
- size_t from = instr->addr;
- size_t len = instr->len;
- int err;
+ loff_t end = instr->addr + instr->len;
+ size_t total_len = instr->len;
+ loff_t from = instr->addr;
+ ssize_t ret;
mutex_lock(&dev->write_mutex);
- err = _block2mtd_erase(dev, from, len);
+ do {
+ size_t len = min_t(size_t, total_len, PAGE_SIZE);
+
+ ret = kernel_write(dev->file, allfs, len, &from);
+ if (ret < 0)
+ goto fail;
+ total_len -= ret;
+ } while (from < end);
mutex_unlock(&dev->write_mutex);
- if (err)
- pr_err("erase failed err = %d\n", err);
- return err;
+ return 0;
+
+fail:
+ pr_err("erase failed err = %zd\n", ret);
+ return ret;
}
@@ -102,72 +79,12 @@ static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, u_char *buf)
{
struct block2mtd_dev *dev = mtd->priv;
- struct page *page;
- pgoff_t index = from >> PAGE_SHIFT;
- int offset = from & (PAGE_SIZE-1);
- int cpylen;
-
- while (len) {
- if ((offset + len) > PAGE_SIZE)
- cpylen = PAGE_SIZE - offset; // multiple pages
- else
- cpylen = len; // this page
- len = len - cpylen;
-
- page = page_read(dev->blkdev->bd_inode->i_mapping, index);
- if (IS_ERR(page))
- return PTR_ERR(page);
-
- memcpy(buf, page_address(page) + offset, cpylen);
- put_page(page);
-
- if (retlen)
- *retlen += cpylen;
- buf += cpylen;
- offset = 0;
- index++;
- }
- return 0;
-}
+ ssize_t ret;
-
-/* write data to the underlying device */
-static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
- loff_t to, size_t len, size_t *retlen)
-{
- struct page *page;
- struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
- pgoff_t index = to >> PAGE_SHIFT; // page index
- int offset = to & ~PAGE_MASK; // page offset
- int cpylen;
-
- while (len) {
- if ((offset+len) > PAGE_SIZE)
- cpylen = PAGE_SIZE - offset; // multiple pages
- else
- cpylen = len; // this page
- len = len - cpylen;
-
- page = page_read(mapping, index);
- if (IS_ERR(page))
- return PTR_ERR(page);
-
- if (memcmp(page_address(page)+offset, buf, cpylen)) {
- lock_page(page);
- memcpy(page_address(page) + offset, buf, cpylen);
- set_page_dirty(page);
- unlock_page(page);
- balance_dirty_pages_ratelimited(mapping);
- }
- put_page(page);
-
- if (retlen)
- *retlen += cpylen;
-
- buf += cpylen;
- offset = 0;
- index++;
- }
+ ret = kernel_read(dev->file, buf, len, &from);
+ if (ret < 0)
+ return ret;
+ *retlen += ret;
return 0;
}
@@ -176,14 +93,17 @@ static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t *retlen, const u_char *buf)
{
struct block2mtd_dev *dev = mtd->priv;
- int err;
+ ssize_t ret;
mutex_lock(&dev->write_mutex);
- err = _block2mtd_write(dev, buf, to, len, retlen);
+ ret = kernel_write(dev->file, buf, len, &to);
+ if (ret > 0) {
+ *retlen += ret;
+ ret = 0;
+ }
mutex_unlock(&dev->write_mutex);
- if (err > 0)
- err = 0;
- return err;
+
+ return ret;
}
@@ -191,8 +111,8 @@ static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
static void block2mtd_sync(struct mtd_info *mtd)
{
struct block2mtd_dev *dev = mtd->priv;
- sync_blockdev(dev->blkdev);
- return;
+
+ vfs_fsync(dev->file, 1);
}
@@ -203,10 +123,9 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
kfree(dev->mtd.name);
- if (dev->blkdev) {
- invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
- 0, -1);
- blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
+ if (dev->file) {
+ vfs_fsync(dev->file, 1);
+ fput(dev->file);
}
kfree(dev);
@@ -216,11 +135,6 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
static struct block2mtd_dev *add_device(char *devname, int erase_size,
int timeout)
{
-#ifndef MODULE
- int i;
-#endif
- const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
- struct block_device *bdev;
struct block2mtd_dev *dev;
char *name;
@@ -231,45 +145,24 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size,
if (!dev)
return NULL;
- /* Get a handle on the device */
- bdev = blkdev_get_by_path(devname, mode, dev);
-
-#ifndef MODULE
- /*
- * We might not have the root device mounted at this point.
- * Try to resolve the device name by other means.
- */
- for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
- dev_t devt;
-
- if (i)
- /*
- * Calling wait_for_device_probe in the first loop
- * was not enough, sleep for a bit in subsequent
- * go-arounds.
- */
- msleep(1000);
- wait_for_device_probe();
-
- devt = name_to_dev_t(devname);
- if (!devt)
- continue;
- bdev = blkdev_get_by_dev(devt, mode, dev);
+ dev->file = filp_open(devname, O_RDWR | O_EXCL, 0);
+ if (IS_ERR(dev->file)) {
+ dev->file = NULL;
+ pr_err("error: cannot open device %s\n", devname);
+ goto err_free_block2mtd;
}
-#endif
- if (IS_ERR(bdev)) {
+ if (!S_ISBLK(file_inode(dev->file)->i_mode)) {
pr_err("error: cannot open device %s\n", devname);
goto err_free_block2mtd;
}
- dev->blkdev = bdev;
- if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
+ if (MAJOR(file_inode(dev->file)->i_rdev) == MTD_BLOCK_MAJOR) {
pr_err("attempting to use an MTD device as a block device\n");
goto err_free_block2mtd;
}
- if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
+ if ((long)i_size_read(dev->file->f_mapping->host) % erase_size) {
pr_err("erasesize must be a divisor of device size\n");
goto err_free_block2mtd;
}
@@ -284,7 +177,7 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size,
dev->mtd.name = name;
- dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
+ dev->mtd.size = i_size_read(dev->file->f_mapping->host) & PAGE_MASK;
dev->mtd.erasesize = erase_size;
dev->mtd.writesize = 1;
dev->mtd.writebufsize = PAGE_SIZE;
--
2.30.2
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