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500 lines
13 KiB
500 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (c) International Business Machines Corp., 2006 |
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* |
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* Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel |
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*/ |
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|
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/* |
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* This is a small driver which implements fake MTD devices on top of UBI |
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* volumes. This sounds strange, but it is in fact quite useful to make |
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* MTD-oriented software (including all the legacy software) work on top of |
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* UBI. |
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* |
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* Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit |
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* size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The |
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* eraseblock size is equivalent to the logical eraseblock size of the volume. |
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*/ |
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|
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#include <linux/err.h> |
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#include <linux/list.h> |
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#include <linux/slab.h> |
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#include <linux/sched.h> |
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#include <linux/math64.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/mtd/ubi.h> |
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#include <linux/mtd/mtd.h> |
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#include "ubi-media.h" |
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|
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#define err_msg(fmt, ...) \ |
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pr_err("gluebi (pid %d): %s: " fmt "\n", \ |
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current->pid, __func__, ##__VA_ARGS__) |
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|
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/** |
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* struct gluebi_device - a gluebi device description data structure. |
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* @mtd: emulated MTD device description object |
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* @refcnt: gluebi device reference count |
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* @desc: UBI volume descriptor |
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* @ubi_num: UBI device number this gluebi device works on |
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* @vol_id: ID of UBI volume this gluebi device works on |
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* @list: link in a list of gluebi devices |
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*/ |
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struct gluebi_device { |
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struct mtd_info mtd; |
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int refcnt; |
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struct ubi_volume_desc *desc; |
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int ubi_num; |
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int vol_id; |
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struct list_head list; |
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}; |
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|
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/* List of all gluebi devices */ |
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static LIST_HEAD(gluebi_devices); |
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static DEFINE_MUTEX(devices_mutex); |
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|
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/** |
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* find_gluebi_nolock - find a gluebi device. |
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* @ubi_num: UBI device number |
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* @vol_id: volume ID |
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* |
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* This function seraches for gluebi device corresponding to UBI device |
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* @ubi_num and UBI volume @vol_id. Returns the gluebi device description |
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* object in case of success and %NULL in case of failure. The caller has to |
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* have the &devices_mutex locked. |
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*/ |
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static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id) |
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{ |
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struct gluebi_device *gluebi; |
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|
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list_for_each_entry(gluebi, &gluebi_devices, list) |
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if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id) |
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return gluebi; |
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return NULL; |
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} |
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/** |
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* gluebi_get_device - get MTD device reference. |
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* @mtd: the MTD device description object |
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* |
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* This function is called every time the MTD device is being opened and |
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* implements the MTD get_device() operation. Returns zero in case of success |
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* and a negative error code in case of failure. |
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*/ |
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static int gluebi_get_device(struct mtd_info *mtd) |
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{ |
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struct gluebi_device *gluebi; |
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int ubi_mode = UBI_READONLY; |
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|
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if (mtd->flags & MTD_WRITEABLE) |
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ubi_mode = UBI_READWRITE; |
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gluebi = container_of(mtd, struct gluebi_device, mtd); |
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mutex_lock(&devices_mutex); |
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if (gluebi->refcnt > 0) { |
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/* |
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* The MTD device is already referenced and this is just one |
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* more reference. MTD allows many users to open the same |
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* volume simultaneously and do not distinguish between |
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* readers/writers/exclusive/meta openers as UBI does. So we do |
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* not open the UBI volume again - just increase the reference |
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* counter and return. |
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*/ |
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gluebi->refcnt += 1; |
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mutex_unlock(&devices_mutex); |
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return 0; |
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} |
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|
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/* |
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* This is the first reference to this UBI volume via the MTD device |
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* interface. Open the corresponding volume in read-write mode. |
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*/ |
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gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id, |
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ubi_mode); |
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if (IS_ERR(gluebi->desc)) { |
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mutex_unlock(&devices_mutex); |
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return PTR_ERR(gluebi->desc); |
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} |
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gluebi->refcnt += 1; |
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mutex_unlock(&devices_mutex); |
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return 0; |
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} |
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/** |
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* gluebi_put_device - put MTD device reference. |
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* @mtd: the MTD device description object |
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* |
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* This function is called every time the MTD device is being put. Returns |
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* zero in case of success and a negative error code in case of failure. |
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*/ |
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static void gluebi_put_device(struct mtd_info *mtd) |
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{ |
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struct gluebi_device *gluebi; |
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gluebi = container_of(mtd, struct gluebi_device, mtd); |
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mutex_lock(&devices_mutex); |
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gluebi->refcnt -= 1; |
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if (gluebi->refcnt == 0) |
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ubi_close_volume(gluebi->desc); |
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mutex_unlock(&devices_mutex); |
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} |
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/** |
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* gluebi_read - read operation of emulated MTD devices. |
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* @mtd: MTD device description object |
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* @from: absolute offset from where to read |
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* @len: how many bytes to read |
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* @retlen: count of read bytes is returned here |
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* @buf: buffer to store the read data |
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* |
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* This function returns zero in case of success and a negative error code in |
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* case of failure. |
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*/ |
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static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len, |
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size_t *retlen, unsigned char *buf) |
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{ |
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int err = 0, lnum, offs, bytes_left; |
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struct gluebi_device *gluebi; |
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gluebi = container_of(mtd, struct gluebi_device, mtd); |
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lnum = div_u64_rem(from, mtd->erasesize, &offs); |
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bytes_left = len; |
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while (bytes_left) { |
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size_t to_read = mtd->erasesize - offs; |
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if (to_read > bytes_left) |
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to_read = bytes_left; |
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err = ubi_read(gluebi->desc, lnum, buf, offs, to_read); |
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if (err) |
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break; |
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lnum += 1; |
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offs = 0; |
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bytes_left -= to_read; |
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buf += to_read; |
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} |
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*retlen = len - bytes_left; |
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return err; |
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} |
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/** |
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* gluebi_write - write operation of emulated MTD devices. |
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* @mtd: MTD device description object |
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* @to: absolute offset where to write |
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* @len: how many bytes to write |
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* @retlen: count of written bytes is returned here |
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* @buf: buffer with data to write |
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* |
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* This function returns zero in case of success and a negative error code in |
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* case of failure. |
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*/ |
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static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len, |
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size_t *retlen, const u_char *buf) |
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{ |
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int err = 0, lnum, offs, bytes_left; |
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struct gluebi_device *gluebi; |
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gluebi = container_of(mtd, struct gluebi_device, mtd); |
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lnum = div_u64_rem(to, mtd->erasesize, &offs); |
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if (len % mtd->writesize || offs % mtd->writesize) |
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return -EINVAL; |
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bytes_left = len; |
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while (bytes_left) { |
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size_t to_write = mtd->erasesize - offs; |
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if (to_write > bytes_left) |
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to_write = bytes_left; |
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err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write); |
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if (err) |
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break; |
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lnum += 1; |
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offs = 0; |
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bytes_left -= to_write; |
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buf += to_write; |
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} |
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*retlen = len - bytes_left; |
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return err; |
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} |
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/** |
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* gluebi_erase - erase operation of emulated MTD devices. |
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* @mtd: the MTD device description object |
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* @instr: the erase operation description |
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* |
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* This function calls the erase callback when finishes. Returns zero in case |
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* of success and a negative error code in case of failure. |
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*/ |
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static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr) |
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{ |
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int err, i, lnum, count; |
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struct gluebi_device *gluebi; |
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if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd)) |
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return -EINVAL; |
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lnum = mtd_div_by_eb(instr->addr, mtd); |
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count = mtd_div_by_eb(instr->len, mtd); |
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gluebi = container_of(mtd, struct gluebi_device, mtd); |
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for (i = 0; i < count - 1; i++) { |
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err = ubi_leb_unmap(gluebi->desc, lnum + i); |
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if (err) |
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goto out_err; |
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} |
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/* |
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* MTD erase operations are synchronous, so we have to make sure the |
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* physical eraseblock is wiped out. |
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* |
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* Thus, perform leb_erase instead of leb_unmap operation - leb_erase |
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* will wait for the end of operations |
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*/ |
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err = ubi_leb_erase(gluebi->desc, lnum + i); |
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if (err) |
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goto out_err; |
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return 0; |
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out_err: |
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instr->fail_addr = (long long)lnum * mtd->erasesize; |
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return err; |
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} |
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/** |
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* gluebi_create - create a gluebi device for an UBI volume. |
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* @di: UBI device description object |
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* @vi: UBI volume description object |
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* |
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* This function is called when a new UBI volume is created in order to create |
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* corresponding fake MTD device. Returns zero in case of success and a |
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* negative error code in case of failure. |
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*/ |
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static int gluebi_create(struct ubi_device_info *di, |
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struct ubi_volume_info *vi) |
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{ |
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struct gluebi_device *gluebi, *g; |
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struct mtd_info *mtd; |
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gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL); |
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if (!gluebi) |
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return -ENOMEM; |
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mtd = &gluebi->mtd; |
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mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL); |
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if (!mtd->name) { |
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kfree(gluebi); |
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return -ENOMEM; |
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} |
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gluebi->vol_id = vi->vol_id; |
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gluebi->ubi_num = vi->ubi_num; |
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mtd->type = MTD_UBIVOLUME; |
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if (!di->ro_mode) |
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mtd->flags = MTD_WRITEABLE; |
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mtd->owner = THIS_MODULE; |
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mtd->writesize = di->min_io_size; |
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mtd->erasesize = vi->usable_leb_size; |
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mtd->_read = gluebi_read; |
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mtd->_write = gluebi_write; |
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mtd->_erase = gluebi_erase; |
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mtd->_get_device = gluebi_get_device; |
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mtd->_put_device = gluebi_put_device; |
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/* |
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* In case of dynamic a volume, MTD device size is just volume size. In |
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* case of a static volume the size is equivalent to the amount of data |
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* bytes. |
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*/ |
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if (vi->vol_type == UBI_DYNAMIC_VOLUME) |
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mtd->size = (unsigned long long)vi->usable_leb_size * vi->size; |
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else |
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mtd->size = vi->used_bytes; |
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/* Just a sanity check - make sure this gluebi device does not exist */ |
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mutex_lock(&devices_mutex); |
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g = find_gluebi_nolock(vi->ubi_num, vi->vol_id); |
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if (g) |
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err_msg("gluebi MTD device %d form UBI device %d volume %d already exists", |
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g->mtd.index, vi->ubi_num, vi->vol_id); |
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mutex_unlock(&devices_mutex); |
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if (mtd_device_register(mtd, NULL, 0)) { |
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err_msg("cannot add MTD device"); |
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kfree(mtd->name); |
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kfree(gluebi); |
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return -ENFILE; |
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} |
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mutex_lock(&devices_mutex); |
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list_add_tail(&gluebi->list, &gluebi_devices); |
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mutex_unlock(&devices_mutex); |
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return 0; |
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} |
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/** |
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* gluebi_remove - remove a gluebi device. |
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* @vi: UBI volume description object |
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* |
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* This function is called when an UBI volume is removed and it removes |
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* corresponding fake MTD device. Returns zero in case of success and a |
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* negative error code in case of failure. |
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*/ |
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static int gluebi_remove(struct ubi_volume_info *vi) |
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{ |
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int err = 0; |
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struct mtd_info *mtd; |
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struct gluebi_device *gluebi; |
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mutex_lock(&devices_mutex); |
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gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id); |
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if (!gluebi) { |
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err_msg("got remove notification for unknown UBI device %d volume %d", |
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vi->ubi_num, vi->vol_id); |
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err = -ENOENT; |
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} else if (gluebi->refcnt) |
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err = -EBUSY; |
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else |
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list_del(&gluebi->list); |
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mutex_unlock(&devices_mutex); |
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if (err) |
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return err; |
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mtd = &gluebi->mtd; |
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err = mtd_device_unregister(mtd); |
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if (err) { |
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err_msg("cannot remove fake MTD device %d, UBI device %d, volume %d, error %d", |
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mtd->index, gluebi->ubi_num, gluebi->vol_id, err); |
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mutex_lock(&devices_mutex); |
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list_add_tail(&gluebi->list, &gluebi_devices); |
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mutex_unlock(&devices_mutex); |
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return err; |
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} |
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kfree(mtd->name); |
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kfree(gluebi); |
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return 0; |
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} |
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/** |
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* gluebi_updated - UBI volume was updated notifier. |
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* @vi: volume info structure |
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* |
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* This function is called every time an UBI volume is updated. It does nothing |
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* if te volume @vol is dynamic, and changes MTD device size if the |
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* volume is static. This is needed because static volumes cannot be read past |
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* data they contain. This function returns zero in case of success and a |
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* negative error code in case of error. |
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*/ |
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static int gluebi_updated(struct ubi_volume_info *vi) |
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{ |
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struct gluebi_device *gluebi; |
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mutex_lock(&devices_mutex); |
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gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id); |
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if (!gluebi) { |
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mutex_unlock(&devices_mutex); |
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err_msg("got update notification for unknown UBI device %d volume %d", |
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vi->ubi_num, vi->vol_id); |
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return -ENOENT; |
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} |
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if (vi->vol_type == UBI_STATIC_VOLUME) |
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gluebi->mtd.size = vi->used_bytes; |
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mutex_unlock(&devices_mutex); |
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return 0; |
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} |
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/** |
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* gluebi_resized - UBI volume was re-sized notifier. |
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* @vi: volume info structure |
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* |
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* This function is called every time an UBI volume is re-size. It changes the |
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* corresponding fake MTD device size. This function returns zero in case of |
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* success and a negative error code in case of error. |
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*/ |
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static int gluebi_resized(struct ubi_volume_info *vi) |
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{ |
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struct gluebi_device *gluebi; |
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mutex_lock(&devices_mutex); |
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gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id); |
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if (!gluebi) { |
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mutex_unlock(&devices_mutex); |
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err_msg("got update notification for unknown UBI device %d volume %d", |
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vi->ubi_num, vi->vol_id); |
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return -ENOENT; |
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} |
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gluebi->mtd.size = vi->used_bytes; |
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mutex_unlock(&devices_mutex); |
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return 0; |
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} |
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/** |
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* gluebi_notify - UBI notification handler. |
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* @nb: registered notifier block |
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* @l: notification type |
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* @ns_ptr: pointer to the &struct ubi_notification object |
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*/ |
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static int gluebi_notify(struct notifier_block *nb, unsigned long l, |
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void *ns_ptr) |
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{ |
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struct ubi_notification *nt = ns_ptr; |
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switch (l) { |
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case UBI_VOLUME_ADDED: |
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gluebi_create(&nt->di, &nt->vi); |
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break; |
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case UBI_VOLUME_REMOVED: |
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gluebi_remove(&nt->vi); |
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break; |
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case UBI_VOLUME_RESIZED: |
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gluebi_resized(&nt->vi); |
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break; |
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case UBI_VOLUME_UPDATED: |
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gluebi_updated(&nt->vi); |
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break; |
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default: |
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break; |
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} |
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return NOTIFY_OK; |
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} |
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static struct notifier_block gluebi_notifier = { |
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.notifier_call = gluebi_notify, |
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}; |
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static int __init ubi_gluebi_init(void) |
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{ |
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return ubi_register_volume_notifier(&gluebi_notifier, 0); |
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} |
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static void __exit ubi_gluebi_exit(void) |
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{ |
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struct gluebi_device *gluebi, *g; |
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list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) { |
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int err; |
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struct mtd_info *mtd = &gluebi->mtd; |
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err = mtd_device_unregister(mtd); |
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if (err) |
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err_msg("error %d while removing gluebi MTD device %d, UBI device %d, volume %d - ignoring", |
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err, mtd->index, gluebi->ubi_num, |
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gluebi->vol_id); |
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kfree(mtd->name); |
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kfree(gluebi); |
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} |
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ubi_unregister_volume_notifier(&gluebi_notifier); |
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} |
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module_init(ubi_gluebi_init); |
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module_exit(ubi_gluebi_exit); |
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MODULE_DESCRIPTION("MTD emulation layer over UBI volumes"); |
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MODULE_AUTHOR("Artem Bityutskiy, Joern Engel"); |
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MODULE_LICENSE("GPL");
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