UBI: introduce volume refcounting
Linux-MTD Mailing List
linux-mtd at lists.infradead.org
Tue Jan 8 02:59:02 EST 2008
Gitweb: http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=d05c77a816974c09f8c7e8f48e5b9f7b59dafdf3
Commit: d05c77a816974c09f8c7e8f48e5b9f7b59dafdf3
Parent: db6e5770ef0ab351a403ac26e1ab1309e58f15d7
Author: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
AuthorDate: Mon Dec 17 15:42:57 2007 +0200
Committer: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
CommitDate: Wed Dec 26 19:15:16 2007 +0200
UBI: introduce volume refcounting
Add ref_count field to UBI volumes and remove weired "vol->removed"
field. This way things are better understandable and we do not have
to do whold show_attr operation under spinlock.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
---
drivers/mtd/ubi/eba.c | 10 +++++
drivers/mtd/ubi/kapi.c | 4 ++-
drivers/mtd/ubi/ubi.h | 22 ++++++------
drivers/mtd/ubi/vmt.c | 88 +++++++++++++++++++++++++++++++----------------
drivers/mtd/ubi/vtbl.c | 2 +
5 files changed, 84 insertions(+), 42 deletions(-)
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 2ff3492..84f7dc9 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -301,6 +301,8 @@ int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
{
int err, pnum, vol_id = vol->vol_id;
+ ubi_assert(vol->ref_count > 0);
+
if (ubi->ro_mode)
return -EROFS;
@@ -349,6 +351,8 @@ int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
struct ubi_vid_hdr *vid_hdr;
uint32_t uninitialized_var(crc);
+ ubi_assert(vol->ref_count > 0);
+
err = leb_read_lock(ubi, vol_id, lnum);
if (err)
return err;
@@ -572,6 +576,8 @@ int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
int err, pnum, tries = 0, vol_id = vol->vol_id;
struct ubi_vid_hdr *vid_hdr;
+ ubi_assert(vol->ref_count > 0);
+
if (ubi->ro_mode)
return -EROFS;
@@ -705,6 +711,8 @@ int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
struct ubi_vid_hdr *vid_hdr;
uint32_t crc;
+ ubi_assert(vol->ref_count > 0);
+
if (ubi->ro_mode)
return -EROFS;
@@ -819,6 +827,8 @@ int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
struct ubi_vid_hdr *vid_hdr;
uint32_t crc;
+ ubi_assert(vol->ref_count > 0);
+
if (ubi->ro_mode)
return -EROFS;
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index 9c28376..780c273 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -152,6 +152,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
break;
}
get_device(&vol->dev);
+ vol->ref_count += 1;
spin_unlock(&ubi->volumes_lock);
desc->vol = vol;
@@ -261,10 +262,11 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
case UBI_EXCLUSIVE:
vol->exclusive = 0;
}
+ vol->ref_count -= 1;
spin_unlock(&vol->ubi->volumes_lock);
- kfree(desc);
put_device(&vol->dev);
+ kfree(desc);
module_put(THIS_MODULE);
}
EXPORT_SYMBOL_GPL(ubi_close_volume);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 69cbee3..f782d5a 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -140,10 +140,10 @@ struct ubi_volume_desc;
* @cdev: character device object to create character device
* @ubi: reference to the UBI device description object
* @vol_id: volume ID
+ * @ref_count: volume reference count
* @readers: number of users holding this volume in read-only mode
* @writers: number of users holding this volume in read-write mode
* @exclusive: whether somebody holds this volume in exclusive mode
- * @removed: if the volume was removed
* @checked: if this static volume was checked
*
* @reserved_pebs: how many physical eraseblocks are reserved for this volume
@@ -156,7 +156,7 @@ struct ubi_volume_desc;
* @corrupted: non-zero if the volume is corrupted (static volumes only)
* @alignment: volume alignment
* @data_pad: how many bytes are not used at the end of physical eraseblocks to
- * satisfy the requested alignment
+ * satisfy the requested alignment
* @name_len: volume name length
* @name: volume name
*
@@ -185,10 +185,10 @@ struct ubi_volume {
struct cdev cdev;
struct ubi_device *ubi;
int vol_id;
+ int ref_count;
int readers;
int writers;
int exclusive;
- int removed;
int checked;
int reserved_pebs;
@@ -242,9 +242,9 @@ struct ubi_wl_entry;
* @vol_count: number of volumes in this UBI device
* @volumes: volumes of this UBI device
* @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
- * @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count, @vol->readers,
- * @vol->writers, @vol->exclusive, @vol->removed, @vol->mapping and
- * @vol->eba_tbl.
+ * @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
+ * @vol->readers, @vol->writers, @vol->exclusive,
+ * @vol->ref_count, @vol->mapping and @vol->eba_tbl.
*
* @rsvd_pebs: count of reserved physical eraseblocks
* @avail_pebs: count of available physical eraseblocks
@@ -273,11 +273,11 @@ struct ubi_wl_entry;
* @prot.pnum: protection tree indexed by physical eraseblock numbers
* @prot.aec: protection tree indexed by absolute erase counter value
* @wl_lock: protects the @used, @free, @prot, @lookuptbl, @abs_ec, @move_from,
- * @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
- * fields
+ * @move_to, @move_to_put @erase_pending, @wl_scheduled, and @works
+ * fields
* @wl_scheduled: non-zero if the wear-leveling was scheduled
* @lookuptbl: a table to quickly find a &struct ubi_wl_entry object for any
- * physical eraseblock
+ * physical eraseblock
* @abs_ec: absolute erase counter
* @move_from: physical eraseblock from where the data is being moved
* @move_to: physical eraseblock where the data is being moved to
@@ -308,13 +308,13 @@ struct ubi_wl_entry;
* @hdrs_min_io_size
* @vid_hdr_shift: contains @vid_hdr_offset - @vid_hdr_aloffset
* @bad_allowed: whether the MTD device admits of bad physical eraseblocks or
- * not
+ * not
* @mtd: MTD device descriptor
*
* @peb_buf1: a buffer of PEB size used for different purposes
* @peb_buf2: another buffer of PEB size used for different purposes
* @buf_mutex: proptects @peb_buf1 and @peb_buf2
- * @dbg_peb_buf: buffer of PEB size used for debugging
+ * @dbg_peb_buf: buffer of PEB size used for debugging
* @dbg_buf_mutex: proptects @dbg_peb_buf
*/
struct ubi_device {
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 3d6ac02..18ef1e1 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -63,21 +63,24 @@ static struct device_attribute attr_vol_upd_marker =
* B. process 2 removes volume Y;
* C. process 1 starts reading the /<sysfs>/class/ubi/ubiX_Y/reserved_ebs file;
*
- * What we want to do in a situation like that is to return error when the file
- * is read. This is done by means of the 'removed' flag and the 'vol_lock' of
- * the UBI volume description object.
+ * In this situation, this function will return %-ENODEV because it will find
+ * out that the volume was removed from the @ubi->volumes array.
*/
static ssize_t vol_attribute_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int ret = -ENODEV;
+ int ret;
struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);
+ struct ubi_device *ubi = vol->ubi;
- spin_lock(&vol->ubi->volumes_lock);
- if (vol->removed) {
- spin_unlock(&vol->ubi->volumes_lock);
- return ret;
+ spin_lock(&ubi->volumes_lock);
+ if (!ubi->volumes[vol->vol_id]) {
+ spin_unlock(&ubi->volumes_lock);
+ return -ENODEV;
}
+ /* Take a reference to prevent volume removal */
+ vol->ref_count += 1;
+ spin_unlock(&ubi->volumes_lock);
if (attr == &attr_vol_reserved_ebs)
ret = sprintf(buf, "%d\n", vol->reserved_pebs);
@@ -102,8 +105,13 @@ static ssize_t vol_attribute_show(struct device *dev,
else if (attr == &attr_vol_upd_marker)
ret = sprintf(buf, "%d\n", vol->upd_marker);
else
- BUG();
- spin_unlock(&vol->ubi->volumes_lock);
+ /* This must be a bug */
+ ret = -EINVAL;
+
+ spin_lock(&ubi->volumes_lock);
+ vol->ref_count -= 1;
+ ubi_assert(vol->ref_count >= 0);
+ spin_unlock(&ubi->volumes_lock);
return ret;
}
@@ -179,7 +187,7 @@ static void volume_sysfs_close(struct ubi_volume *vol)
* @req: volume creation request
*
* This function creates volume described by @req. If @req->vol_id id
- * %UBI_VOL_NUM_AUTO, this function automatically assigne ID to the new volume
+ * %UBI_VOL_NUM_AUTO, this function automatically assign ID to the new volume
* and saves it in @req->vol_id. Returns zero in case of success and a negative
* error code in case of failure.
*/
@@ -261,7 +269,6 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
memcpy(vol->name, req->name, vol->name_len + 1);
vol->exclusive = 1;
vol->ubi = ubi;
- ubi->volumes[vol_id] = vol;
spin_unlock(&ubi->volumes_lock);
/*
@@ -345,6 +352,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
spin_lock(&ubi->volumes_lock);
ubi->vol_count += 1;
vol->exclusive = 0;
+ ubi->volumes[vol_id] = vol;
spin_unlock(&ubi->volumes_lock);
paranoid_check_volumes(ubi);
@@ -353,7 +361,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
out_sysfs:
/*
- * We have degistered our device, we should not free the volume*
+ * We have registered our device, we should not free the volume*
* description object in this function in case of an error - it is
* freed by the release function.
*
@@ -373,7 +381,6 @@ out_acc:
spin_lock(&ubi->volumes_lock);
ubi->rsvd_pebs -= vol->reserved_pebs;
ubi->avail_pebs += vol->reserved_pebs;
- ubi->volumes[vol_id] = NULL;
out_unlock:
spin_unlock(&ubi->volumes_lock);
mutex_unlock(&ubi->volumes_mutex);
@@ -407,25 +414,32 @@ int ubi_remove_volume(struct ubi_volume_desc *desc)
return -EROFS;
mutex_lock(&ubi->volumes_mutex);
+ spin_lock(&ubi->volumes_lock);
+ if (vol->ref_count > 1) {
+ /*
+ * The volume is busy, probably someone is reading one of its
+ * sysfs files.
+ */
+ err = -EBUSY;
+ goto out_unlock;
+ }
+ ubi->volumes[vol_id] = NULL;
+ spin_unlock(&ubi->volumes_lock);
+
err = ubi_destroy_gluebi(vol);
if (err)
- goto out;
+ goto out_err;
err = ubi_change_vtbl_record(ubi, vol_id, NULL);
if (err)
- goto out;
+ goto out_err;
for (i = 0; i < vol->reserved_pebs; i++) {
err = ubi_eba_unmap_leb(ubi, vol, i);
if (err)
- goto out;
+ goto out_err;
}
- spin_lock(&ubi->volumes_lock);
- vol->removed = 1;
- ubi->volumes[vol_id] = NULL;
- spin_unlock(&ubi->volumes_lock);
-
kfree(vol->eba_tbl);
vol->eba_tbl = NULL;
cdev_del(&vol->cdev);
@@ -447,7 +461,15 @@ int ubi_remove_volume(struct ubi_volume_desc *desc)
spin_unlock(&ubi->volumes_lock);
paranoid_check_volumes(ubi);
-out:
+ mutex_unlock(&ubi->volumes_mutex);
+ return 0;
+
+out_err:
+ ubi_err("cannot remove volume %d, error %d", vol_id, err);
+ spin_lock(&ubi->volumes_lock);
+ ubi->volumes[vol_id] = vol;
+out_unlock:
+ spin_unlock(&ubi->volumes_lock);
mutex_unlock(&ubi->volumes_mutex);
return err;
}
@@ -494,8 +516,17 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
for (i = 0; i < reserved_pebs; i++)
new_mapping[i] = UBI_LEB_UNMAPPED;
- /* Reserve physical eraseblocks */
mutex_lock(&ubi->volumes_mutex);
+ spin_lock(&ubi->volumes_lock);
+ if (vol->ref_count > 1) {
+ spin_unlock(&ubi->volumes_lock);
+ err = -EBUSY;
+ goto out_free;
+ }
+ spin_unlock(&ubi->volumes_lock);
+
+
+ /* Reserve physical eraseblocks */
pebs = reserved_pebs - vol->reserved_pebs;
if (pebs > 0) {
spin_lock(&ubi->volumes_lock);
@@ -577,8 +608,8 @@ out_free:
* @ubi: UBI device description object
* @vol: volume description object
*
- * This function adds an existin volume and initializes all its data
- * structures. Returnes zero in case of success and a negative error code in
+ * This function adds an existing volume and initializes all its data
+ * structures. Returns zero in case of success and a negative error code in
* case of failure.
*/
int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
@@ -588,7 +619,6 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
dbg_msg("add volume %d", vol_id);
ubi_dbg_dump_vol_info(vol);
- ubi_assert(vol);
/* Register character device for the volume */
cdev_init(&vol->cdev, &ubi_vol_cdev_operations);
@@ -645,11 +675,9 @@ void ubi_free_volume(struct ubi_device *ubi, struct ubi_volume *vol)
int err;
dbg_msg("free volume %d", vol->vol_id);
- ubi_assert(vol);
- vol->removed = 1;
- err = ubi_destroy_gluebi(vol);
ubi->volumes[vol->vol_id] = NULL;
+ err = ubi_destroy_gluebi(vol);
cdev_del(&vol->cdev);
volume_sysfs_close(vol);
}
diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index 5879fdb..a37dc7a 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -565,6 +565,7 @@ static int init_volumes(struct ubi_device *ubi, const struct ubi_scan_info *si,
vol->last_eb_bytes = sv->last_data_size;
}
+ /* And add the layout volume */
vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
if (!vol)
return -ENOMEM;
@@ -580,6 +581,7 @@ static int init_volumes(struct ubi_device *ubi, const struct ubi_scan_info *si,
vol->used_bytes =
(long long)vol->used_ebs * (ubi->leb_size - vol->data_pad);
vol->vol_id = UBI_LAYOUT_VOL_ID;
+ vol->ref_count = 1;
ubi_assert(!ubi->volumes[i]);
ubi->volumes[vol_id2idx(ubi, vol->vol_id)] = vol;
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