linux/fs/block_dev.c
Linus Torvalds 088737f44b Writeback error handling fixes (pile #2)
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Merge tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

Pull Writeback error handling updates from Jeff Layton:
 "This pile represents the bulk of the writeback error handling fixes
  that I have for this cycle. Some of the earlier patches in this pile
  may look trivial but they are prerequisites for later patches in the
  series.

  The aim of this set is to improve how we track and report writeback
  errors to userland. Most applications that care about data integrity
  will periodically call fsync/fdatasync/msync to ensure that their
  writes have made it to the backing store.

  For a very long time, we have tracked writeback errors using two flags
  in the address_space: AS_EIO and AS_ENOSPC. Those flags are set when a
  writeback error occurs (via mapping_set_error) and are cleared as a
  side-effect of filemap_check_errors (as you noted yesterday). This
  model really sucks for userland.

  Only the first task to call fsync (or msync or fdatasync) will see the
  error. Any subsequent task calling fsync on a file will get back 0
  (unless another writeback error occurs in the interim). If I have
  several tasks writing to a file and calling fsync to ensure that their
  writes got stored, then I need to have them coordinate with one
  another. That's difficult enough, but in a world of containerized
  setups that coordination may even not be possible.

  But wait...it gets worse!

  The calls to filemap_check_errors can be buried pretty far down in the
  call stack, and there are internal callers of filemap_write_and_wait
  and the like that also end up clearing those errors. Many of those
  callers ignore the error return from that function or return it to
  userland at nonsensical times (e.g. truncate() or stat()). If I get
  back -EIO on a truncate, there is no reason to think that it was
  because some previous writeback failed, and a subsequent fsync() will
  (incorrectly) return 0.

  This pile aims to do three things:

   1) ensure that when a writeback error occurs that that error will be
      reported to userland on a subsequent fsync/fdatasync/msync call,
      regardless of what internal callers are doing

   2) report writeback errors on all file descriptions that were open at
      the time that the error occurred. This is a user-visible change,
      but I think most applications are written to assume this behavior
      anyway. Those that aren't are unlikely to be hurt by it.

   3) document what filesystems should do when there is a writeback
      error. Today, there is very little consistency between them, and a
      lot of cargo-cult copying. We need to make it very clear what
      filesystems should do in this situation.

  To achieve this, the set adds a new data type (errseq_t) and then
  builds new writeback error tracking infrastructure around that. Once
  all of that is in place, we change the filesystems to use the new
  infrastructure for reporting wb errors to userland.

  Note that this is just the initial foray into cleaning up this mess.
  There is a lot of work remaining here:

   1) convert the rest of the filesystems in a similar fashion. Once the
      initial set is in, then I think most other fs' will be fairly
      simple to convert. Hopefully most of those can in via individual
      filesystem trees.

   2) convert internal waiters on writeback to use errseq_t for
      detecting errors instead of relying on the AS_* flags. I have some
      draft patches for this for ext4, but they are not quite ready for
      prime time yet.

  This was a discussion topic this year at LSF/MM too. If you're
  interested in the gory details, LWN has some good articles about this:

      https://lwn.net/Articles/718734/
      https://lwn.net/Articles/724307/"

* tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  btrfs: minimal conversion to errseq_t writeback error reporting on fsync
  xfs: minimal conversion to errseq_t writeback error reporting
  ext4: use errseq_t based error handling for reporting data writeback errors
  fs: convert __generic_file_fsync to use errseq_t based reporting
  block: convert to errseq_t based writeback error tracking
  dax: set errors in mapping when writeback fails
  Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors
  mm: set both AS_EIO/AS_ENOSPC and errseq_t in mapping_set_error
  fs: new infrastructure for writeback error handling and reporting
  lib: add errseq_t type and infrastructure for handling it
  mm: don't TestClearPageError in __filemap_fdatawait_range
  mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails
  jbd2: don't clear and reset errors after waiting on writeback
  buffer: set errors in mapping at the time that the error occurs
  fs: check for writeback errors after syncing out buffers in generic_file_fsync
  buffer: use mapping_set_error instead of setting the flag
  mm: fix mapping_set_error call in me_pagecache_dirty
2017-07-07 19:38:17 -07:00

2159 lines
53 KiB
C

/*
* linux/fs/block_dev.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
*/
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/major.h>
#include <linux/device_cgroup.h>
#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/module.h>
#include <linux/blkpg.h>
#include <linux/magic.h>
#include <linux/dax.h>
#include <linux/buffer_head.h>
#include <linux/swap.h>
#include <linux/pagevec.h>
#include <linux/writeback.h>
#include <linux/mpage.h>
#include <linux/mount.h>
#include <linux/uio.h>
#include <linux/namei.h>
#include <linux/log2.h>
#include <linux/cleancache.h>
#include <linux/dax.h>
#include <linux/badblocks.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/falloc.h>
#include <linux/uaccess.h>
#include "internal.h"
struct bdev_inode {
struct block_device bdev;
struct inode vfs_inode;
};
static const struct address_space_operations def_blk_aops;
static inline struct bdev_inode *BDEV_I(struct inode *inode)
{
return container_of(inode, struct bdev_inode, vfs_inode);
}
struct block_device *I_BDEV(struct inode *inode)
{
return &BDEV_I(inode)->bdev;
}
EXPORT_SYMBOL(I_BDEV);
void __vfs_msg(struct super_block *sb, const char *prefix, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
printk_ratelimited("%sVFS (%s): %pV\n", prefix, sb->s_id, &vaf);
va_end(args);
}
static void bdev_write_inode(struct block_device *bdev)
{
struct inode *inode = bdev->bd_inode;
int ret;
spin_lock(&inode->i_lock);
while (inode->i_state & I_DIRTY) {
spin_unlock(&inode->i_lock);
ret = write_inode_now(inode, true);
if (ret) {
char name[BDEVNAME_SIZE];
pr_warn_ratelimited("VFS: Dirty inode writeback failed "
"for block device %s (err=%d).\n",
bdevname(bdev, name), ret);
}
spin_lock(&inode->i_lock);
}
spin_unlock(&inode->i_lock);
}
/* Kill _all_ buffers and pagecache , dirty or not.. */
void kill_bdev(struct block_device *bdev)
{
struct address_space *mapping = bdev->bd_inode->i_mapping;
if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
return;
invalidate_bh_lrus();
truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(kill_bdev);
/* Invalidate clean unused buffers and pagecache. */
void invalidate_bdev(struct block_device *bdev)
{
struct address_space *mapping = bdev->bd_inode->i_mapping;
if (mapping->nrpages) {
invalidate_bh_lrus();
lru_add_drain_all(); /* make sure all lru add caches are flushed */
invalidate_mapping_pages(mapping, 0, -1);
}
/* 99% of the time, we don't need to flush the cleancache on the bdev.
* But, for the strange corners, lets be cautious
*/
cleancache_invalidate_inode(mapping);
}
EXPORT_SYMBOL(invalidate_bdev);
int set_blocksize(struct block_device *bdev, int size)
{
/* Size must be a power of two, and between 512 and PAGE_SIZE */
if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
return -EINVAL;
/* Size cannot be smaller than the size supported by the device */
if (size < bdev_logical_block_size(bdev))
return -EINVAL;
/* Don't change the size if it is same as current */
if (bdev->bd_block_size != size) {
sync_blockdev(bdev);
bdev->bd_block_size = size;
bdev->bd_inode->i_blkbits = blksize_bits(size);
kill_bdev(bdev);
}
return 0;
}
EXPORT_SYMBOL(set_blocksize);
int sb_set_blocksize(struct super_block *sb, int size)
{
if (set_blocksize(sb->s_bdev, size))
return 0;
/* If we get here, we know size is power of two
* and it's value is between 512 and PAGE_SIZE */
sb->s_blocksize = size;
sb->s_blocksize_bits = blksize_bits(size);
return sb->s_blocksize;
}
EXPORT_SYMBOL(sb_set_blocksize);
int sb_min_blocksize(struct super_block *sb, int size)
{
int minsize = bdev_logical_block_size(sb->s_bdev);
if (size < minsize)
size = minsize;
return sb_set_blocksize(sb, size);
}
EXPORT_SYMBOL(sb_min_blocksize);
static int
blkdev_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
bh->b_bdev = I_BDEV(inode);
bh->b_blocknr = iblock;
set_buffer_mapped(bh);
return 0;
}
static struct inode *bdev_file_inode(struct file *file)
{
return file->f_mapping->host;
}
static unsigned int dio_bio_write_op(struct kiocb *iocb)
{
unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
/* avoid the need for a I/O completion work item */
if (iocb->ki_flags & IOCB_DSYNC)
op |= REQ_FUA;
return op;
}
#define DIO_INLINE_BIO_VECS 4
static void blkdev_bio_end_io_simple(struct bio *bio)
{
struct task_struct *waiter = bio->bi_private;
WRITE_ONCE(bio->bi_private, NULL);
wake_up_process(waiter);
}
static ssize_t
__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
int nr_pages)
{
struct file *file = iocb->ki_filp;
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs, *bvec;
loff_t pos = iocb->ki_pos;
bool should_dirty = false;
struct bio bio;
ssize_t ret;
blk_qc_t qc;
int i;
if ((pos | iov_iter_alignment(iter)) &
(bdev_logical_block_size(bdev) - 1))
return -EINVAL;
if (nr_pages <= DIO_INLINE_BIO_VECS)
vecs = inline_vecs;
else {
vecs = kmalloc(nr_pages * sizeof(struct bio_vec), GFP_KERNEL);
if (!vecs)
return -ENOMEM;
}
bio_init(&bio, vecs, nr_pages);
bio.bi_bdev = bdev;
bio.bi_iter.bi_sector = pos >> 9;
bio.bi_write_hint = iocb->ki_hint;
bio.bi_private = current;
bio.bi_end_io = blkdev_bio_end_io_simple;
ret = bio_iov_iter_get_pages(&bio, iter);
if (unlikely(ret))
return ret;
ret = bio.bi_iter.bi_size;
if (iov_iter_rw(iter) == READ) {
bio.bi_opf = REQ_OP_READ;
if (iter_is_iovec(iter))
should_dirty = true;
} else {
bio.bi_opf = dio_bio_write_op(iocb);
task_io_account_write(ret);
}
qc = submit_bio(&bio);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!READ_ONCE(bio.bi_private))
break;
if (!(iocb->ki_flags & IOCB_HIPRI) ||
!blk_mq_poll(bdev_get_queue(bdev), qc))
io_schedule();
}
__set_current_state(TASK_RUNNING);
bio_for_each_segment_all(bvec, &bio, i) {
if (should_dirty && !PageCompound(bvec->bv_page))
set_page_dirty_lock(bvec->bv_page);
put_page(bvec->bv_page);
}
if (vecs != inline_vecs)
kfree(vecs);
if (unlikely(bio.bi_status))
ret = blk_status_to_errno(bio.bi_status);
bio_uninit(&bio);
return ret;
}
struct blkdev_dio {
union {
struct kiocb *iocb;
struct task_struct *waiter;
};
size_t size;
atomic_t ref;
bool multi_bio : 1;
bool should_dirty : 1;
bool is_sync : 1;
struct bio bio;
};
static struct bio_set *blkdev_dio_pool __read_mostly;
static void blkdev_bio_end_io(struct bio *bio)
{
struct blkdev_dio *dio = bio->bi_private;
bool should_dirty = dio->should_dirty;
if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) {
if (bio->bi_status && !dio->bio.bi_status)
dio->bio.bi_status = bio->bi_status;
} else {
if (!dio->is_sync) {
struct kiocb *iocb = dio->iocb;
ssize_t ret;
if (likely(!dio->bio.bi_status)) {
ret = dio->size;
iocb->ki_pos += ret;
} else {
ret = blk_status_to_errno(dio->bio.bi_status);
}
dio->iocb->ki_complete(iocb, ret, 0);
bio_put(&dio->bio);
} else {
struct task_struct *waiter = dio->waiter;
WRITE_ONCE(dio->waiter, NULL);
wake_up_process(waiter);
}
}
if (should_dirty) {
bio_check_pages_dirty(bio);
} else {
struct bio_vec *bvec;
int i;
bio_for_each_segment_all(bvec, bio, i)
put_page(bvec->bv_page);
bio_put(bio);
}
}
static ssize_t
__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
{
struct file *file = iocb->ki_filp;
struct inode *inode = bdev_file_inode(file);
struct block_device *bdev = I_BDEV(inode);
struct blk_plug plug;
struct blkdev_dio *dio;
struct bio *bio;
bool is_read = (iov_iter_rw(iter) == READ), is_sync;
loff_t pos = iocb->ki_pos;
blk_qc_t qc = BLK_QC_T_NONE;
int ret = 0;
if ((pos | iov_iter_alignment(iter)) &
(bdev_logical_block_size(bdev) - 1))
return -EINVAL;
bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, blkdev_dio_pool);
bio_get(bio); /* extra ref for the completion handler */
dio = container_of(bio, struct blkdev_dio, bio);
dio->is_sync = is_sync = is_sync_kiocb(iocb);
if (dio->is_sync)
dio->waiter = current;
else
dio->iocb = iocb;
dio->size = 0;
dio->multi_bio = false;
dio->should_dirty = is_read && (iter->type == ITER_IOVEC);
blk_start_plug(&plug);
for (;;) {
bio->bi_bdev = bdev;
bio->bi_iter.bi_sector = pos >> 9;
bio->bi_write_hint = iocb->ki_hint;
bio->bi_private = dio;
bio->bi_end_io = blkdev_bio_end_io;
ret = bio_iov_iter_get_pages(bio, iter);
if (unlikely(ret)) {
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
break;
}
if (is_read) {
bio->bi_opf = REQ_OP_READ;
if (dio->should_dirty)
bio_set_pages_dirty(bio);
} else {
bio->bi_opf = dio_bio_write_op(iocb);
task_io_account_write(bio->bi_iter.bi_size);
}
dio->size += bio->bi_iter.bi_size;
pos += bio->bi_iter.bi_size;
nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
if (!nr_pages) {
qc = submit_bio(bio);
break;
}
if (!dio->multi_bio) {
dio->multi_bio = true;
atomic_set(&dio->ref, 2);
} else {
atomic_inc(&dio->ref);
}
submit_bio(bio);
bio = bio_alloc(GFP_KERNEL, nr_pages);
}
blk_finish_plug(&plug);
if (!is_sync)
return -EIOCBQUEUED;
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!READ_ONCE(dio->waiter))
break;
if (!(iocb->ki_flags & IOCB_HIPRI) ||
!blk_mq_poll(bdev_get_queue(bdev), qc))
io_schedule();
}
__set_current_state(TASK_RUNNING);
if (!ret)
ret = blk_status_to_errno(dio->bio.bi_status);
if (likely(!ret))
ret = dio->size;
bio_put(&dio->bio);
return ret;
}
static ssize_t
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
int nr_pages;
nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1);
if (!nr_pages)
return 0;
if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
}
static __init int blkdev_init(void)
{
blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
if (!blkdev_dio_pool)
return -ENOMEM;
return 0;
}
module_init(blkdev_init);
int __sync_blockdev(struct block_device *bdev, int wait)
{
if (!bdev)
return 0;
if (!wait)
return filemap_flush(bdev->bd_inode->i_mapping);
return filemap_write_and_wait(bdev->bd_inode->i_mapping);
}
/*
* Write out and wait upon all the dirty data associated with a block
* device via its mapping. Does not take the superblock lock.
*/
int sync_blockdev(struct block_device *bdev)
{
return __sync_blockdev(bdev, 1);
}
EXPORT_SYMBOL(sync_blockdev);
/*
* Write out and wait upon all dirty data associated with this
* device. Filesystem data as well as the underlying block
* device. Takes the superblock lock.
*/
int fsync_bdev(struct block_device *bdev)
{
struct super_block *sb = get_super(bdev);
if (sb) {
int res = sync_filesystem(sb);
drop_super(sb);
return res;
}
return sync_blockdev(bdev);
}
EXPORT_SYMBOL(fsync_bdev);
/**
* freeze_bdev -- lock a filesystem and force it into a consistent state
* @bdev: blockdevice to lock
*
* If a superblock is found on this device, we take the s_umount semaphore
* on it to make sure nobody unmounts until the snapshot creation is done.
* The reference counter (bd_fsfreeze_count) guarantees that only the last
* unfreeze process can unfreeze the frozen filesystem actually when multiple
* freeze requests arrive simultaneously. It counts up in freeze_bdev() and
* count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
* actually.
*/
struct super_block *freeze_bdev(struct block_device *bdev)
{
struct super_block *sb;
int error = 0;
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (++bdev->bd_fsfreeze_count > 1) {
/*
* We don't even need to grab a reference - the first call
* to freeze_bdev grab an active reference and only the last
* thaw_bdev drops it.
*/
sb = get_super(bdev);
if (sb)
drop_super(sb);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return sb;
}
sb = get_active_super(bdev);
if (!sb)
goto out;
if (sb->s_op->freeze_super)
error = sb->s_op->freeze_super(sb);
else
error = freeze_super(sb);
if (error) {
deactivate_super(sb);
bdev->bd_fsfreeze_count--;
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return ERR_PTR(error);
}
deactivate_super(sb);
out:
sync_blockdev(bdev);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return sb; /* thaw_bdev releases s->s_umount */
}
EXPORT_SYMBOL(freeze_bdev);
/**
* thaw_bdev -- unlock filesystem
* @bdev: blockdevice to unlock
* @sb: associated superblock
*
* Unlocks the filesystem and marks it writeable again after freeze_bdev().
*/
int thaw_bdev(struct block_device *bdev, struct super_block *sb)
{
int error = -EINVAL;
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (!bdev->bd_fsfreeze_count)
goto out;
error = 0;
if (--bdev->bd_fsfreeze_count > 0)
goto out;
if (!sb)
goto out;
if (sb->s_op->thaw_super)
error = sb->s_op->thaw_super(sb);
else
error = thaw_super(sb);
if (error)
bdev->bd_fsfreeze_count++;
out:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return error;
}
EXPORT_SYMBOL(thaw_bdev);
static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, blkdev_get_block, wbc);
}
static int blkdev_readpage(struct file * file, struct page * page)
{
return block_read_full_page(page, blkdev_get_block);
}
static int blkdev_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
}
static int blkdev_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
return block_write_begin(mapping, pos, len, flags, pagep,
blkdev_get_block);
}
static int blkdev_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
int ret;
ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
unlock_page(page);
put_page(page);
return ret;
}
/*
* private llseek:
* for a block special file file_inode(file)->i_size is zero
* so we compute the size by hand (just as in block_read/write above)
*/
static loff_t block_llseek(struct file *file, loff_t offset, int whence)
{
struct inode *bd_inode = bdev_file_inode(file);
loff_t retval;
inode_lock(bd_inode);
retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
inode_unlock(bd_inode);
return retval;
}
int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
struct inode *bd_inode = bdev_file_inode(filp);
struct block_device *bdev = I_BDEV(bd_inode);
int error;
error = file_write_and_wait_range(filp, start, end);
if (error)
return error;
/*
* There is no need to serialise calls to blkdev_issue_flush with
* i_mutex and doing so causes performance issues with concurrent
* O_SYNC writers to a block device.
*/
error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
if (error == -EOPNOTSUPP)
error = 0;
return error;
}
EXPORT_SYMBOL(blkdev_fsync);
/**
* bdev_read_page() - Start reading a page from a block device
* @bdev: The device to read the page from
* @sector: The offset on the device to read the page to (need not be aligned)
* @page: The page to read
*
* On entry, the page should be locked. It will be unlocked when the page
* has been read. If the block driver implements rw_page synchronously,
* that will be true on exit from this function, but it need not be.
*
* Errors returned by this function are usually "soft", eg out of memory, or
* queue full; callers should try a different route to read this page rather
* than propagate an error back up the stack.
*
* Return: negative errno if an error occurs, 0 if submission was successful.
*/
int bdev_read_page(struct block_device *bdev, sector_t sector,
struct page *page)
{
const struct block_device_operations *ops = bdev->bd_disk->fops;
int result = -EOPNOTSUPP;
if (!ops->rw_page || bdev_get_integrity(bdev))
return result;
result = blk_queue_enter(bdev->bd_queue, false);
if (result)
return result;
result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false);
blk_queue_exit(bdev->bd_queue);
return result;
}
EXPORT_SYMBOL_GPL(bdev_read_page);
/**
* bdev_write_page() - Start writing a page to a block device
* @bdev: The device to write the page to
* @sector: The offset on the device to write the page to (need not be aligned)
* @page: The page to write
* @wbc: The writeback_control for the write
*
* On entry, the page should be locked and not currently under writeback.
* On exit, if the write started successfully, the page will be unlocked and
* under writeback. If the write failed already (eg the driver failed to
* queue the page to the device), the page will still be locked. If the
* caller is a ->writepage implementation, it will need to unlock the page.
*
* Errors returned by this function are usually "soft", eg out of memory, or
* queue full; callers should try a different route to write this page rather
* than propagate an error back up the stack.
*
* Return: negative errno if an error occurs, 0 if submission was successful.
*/
int bdev_write_page(struct block_device *bdev, sector_t sector,
struct page *page, struct writeback_control *wbc)
{
int result;
const struct block_device_operations *ops = bdev->bd_disk->fops;
if (!ops->rw_page || bdev_get_integrity(bdev))
return -EOPNOTSUPP;
result = blk_queue_enter(bdev->bd_queue, false);
if (result)
return result;
set_page_writeback(page);
result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true);
if (result)
end_page_writeback(page);
else
unlock_page(page);
blk_queue_exit(bdev->bd_queue);
return result;
}
EXPORT_SYMBOL_GPL(bdev_write_page);
/*
* pseudo-fs
*/
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
static struct kmem_cache * bdev_cachep __read_mostly;
static struct inode *bdev_alloc_inode(struct super_block *sb)
{
struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
if (!ei)
return NULL;
return &ei->vfs_inode;
}
static void bdev_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
struct bdev_inode *bdi = BDEV_I(inode);
kmem_cache_free(bdev_cachep, bdi);
}
static void bdev_destroy_inode(struct inode *inode)
{
call_rcu(&inode->i_rcu, bdev_i_callback);
}
static void init_once(void *foo)
{
struct bdev_inode *ei = (struct bdev_inode *) foo;
struct block_device *bdev = &ei->bdev;
memset(bdev, 0, sizeof(*bdev));
mutex_init(&bdev->bd_mutex);
INIT_LIST_HEAD(&bdev->bd_list);
#ifdef CONFIG_SYSFS
INIT_LIST_HEAD(&bdev->bd_holder_disks);
#endif
bdev->bd_bdi = &noop_backing_dev_info;
inode_init_once(&ei->vfs_inode);
/* Initialize mutex for freeze. */
mutex_init(&bdev->bd_fsfreeze_mutex);
}
static void bdev_evict_inode(struct inode *inode)
{
struct block_device *bdev = &BDEV_I(inode)->bdev;
truncate_inode_pages_final(&inode->i_data);
invalidate_inode_buffers(inode); /* is it needed here? */
clear_inode(inode);
spin_lock(&bdev_lock);
list_del_init(&bdev->bd_list);
spin_unlock(&bdev_lock);
/* Detach inode from wb early as bdi_put() may free bdi->wb */
inode_detach_wb(inode);
if (bdev->bd_bdi != &noop_backing_dev_info) {
bdi_put(bdev->bd_bdi);
bdev->bd_bdi = &noop_backing_dev_info;
}
}
static const struct super_operations bdev_sops = {
.statfs = simple_statfs,
.alloc_inode = bdev_alloc_inode,
.destroy_inode = bdev_destroy_inode,
.drop_inode = generic_delete_inode,
.evict_inode = bdev_evict_inode,
};
static struct dentry *bd_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
struct dentry *dent;
dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
if (!IS_ERR(dent))
dent->d_sb->s_iflags |= SB_I_CGROUPWB;
return dent;
}
static struct file_system_type bd_type = {
.name = "bdev",
.mount = bd_mount,
.kill_sb = kill_anon_super,
};
struct super_block *blockdev_superblock __read_mostly;
EXPORT_SYMBOL_GPL(blockdev_superblock);
void __init bdev_cache_init(void)
{
int err;
static struct vfsmount *bd_mnt;
bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
init_once);
err = register_filesystem(&bd_type);
if (err)
panic("Cannot register bdev pseudo-fs");
bd_mnt = kern_mount(&bd_type);
if (IS_ERR(bd_mnt))
panic("Cannot create bdev pseudo-fs");
blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
}
/*
* Most likely _very_ bad one - but then it's hardly critical for small
* /dev and can be fixed when somebody will need really large one.
* Keep in mind that it will be fed through icache hash function too.
*/
static inline unsigned long hash(dev_t dev)
{
return MAJOR(dev)+MINOR(dev);
}
static int bdev_test(struct inode *inode, void *data)
{
return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
}
static int bdev_set(struct inode *inode, void *data)
{
BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
return 0;
}
static LIST_HEAD(all_bdevs);
/*
* If there is a bdev inode for this device, unhash it so that it gets evicted
* as soon as last inode reference is dropped.
*/
void bdev_unhash_inode(dev_t dev)
{
struct inode *inode;
inode = ilookup5(blockdev_superblock, hash(dev), bdev_test, &dev);
if (inode) {
remove_inode_hash(inode);
iput(inode);
}
}
struct block_device *bdget(dev_t dev)
{
struct block_device *bdev;
struct inode *inode;
inode = iget5_locked(blockdev_superblock, hash(dev),
bdev_test, bdev_set, &dev);
if (!inode)
return NULL;
bdev = &BDEV_I(inode)->bdev;
if (inode->i_state & I_NEW) {
bdev->bd_contains = NULL;
bdev->bd_super = NULL;
bdev->bd_inode = inode;
bdev->bd_block_size = i_blocksize(inode);
bdev->bd_part_count = 0;
bdev->bd_invalidated = 0;
inode->i_mode = S_IFBLK;
inode->i_rdev = dev;
inode->i_bdev = bdev;
inode->i_data.a_ops = &def_blk_aops;
mapping_set_gfp_mask(&inode->i_data, GFP_USER);
spin_lock(&bdev_lock);
list_add(&bdev->bd_list, &all_bdevs);
spin_unlock(&bdev_lock);
unlock_new_inode(inode);
}
return bdev;
}
EXPORT_SYMBOL(bdget);
/**
* bdgrab -- Grab a reference to an already referenced block device
* @bdev: Block device to grab a reference to.
*/
struct block_device *bdgrab(struct block_device *bdev)
{
ihold(bdev->bd_inode);
return bdev;
}
EXPORT_SYMBOL(bdgrab);
long nr_blockdev_pages(void)
{
struct block_device *bdev;
long ret = 0;
spin_lock(&bdev_lock);
list_for_each_entry(bdev, &all_bdevs, bd_list) {
ret += bdev->bd_inode->i_mapping->nrpages;
}
spin_unlock(&bdev_lock);
return ret;
}
void bdput(struct block_device *bdev)
{
iput(bdev->bd_inode);
}
EXPORT_SYMBOL(bdput);
static struct block_device *bd_acquire(struct inode *inode)
{
struct block_device *bdev;
spin_lock(&bdev_lock);
bdev = inode->i_bdev;
if (bdev && !inode_unhashed(bdev->bd_inode)) {
bdgrab(bdev);
spin_unlock(&bdev_lock);
return bdev;
}
spin_unlock(&bdev_lock);
/*
* i_bdev references block device inode that was already shut down
* (corresponding device got removed). Remove the reference and look
* up block device inode again just in case new device got
* reestablished under the same device number.
*/
if (bdev)
bd_forget(inode);
bdev = bdget(inode->i_rdev);
if (bdev) {
spin_lock(&bdev_lock);
if (!inode->i_bdev) {
/*
* We take an additional reference to bd_inode,
* and it's released in clear_inode() of inode.
* So, we can access it via ->i_mapping always
* without igrab().
*/
bdgrab(bdev);
inode->i_bdev = bdev;
inode->i_mapping = bdev->bd_inode->i_mapping;
}
spin_unlock(&bdev_lock);
}
return bdev;
}
/* Call when you free inode */
void bd_forget(struct inode *inode)
{
struct block_device *bdev = NULL;
spin_lock(&bdev_lock);
if (!sb_is_blkdev_sb(inode->i_sb))
bdev = inode->i_bdev;
inode->i_bdev = NULL;
inode->i_mapping = &inode->i_data;
spin_unlock(&bdev_lock);
if (bdev)
bdput(bdev);
}
/**
* bd_may_claim - test whether a block device can be claimed
* @bdev: block device of interest
* @whole: whole block device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Test whether @bdev can be claimed by @holder.
*
* CONTEXT:
* spin_lock(&bdev_lock).
*
* RETURNS:
* %true if @bdev can be claimed, %false otherwise.
*/
static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
void *holder)
{
if (bdev->bd_holder == holder)
return true; /* already a holder */
else if (bdev->bd_holder != NULL)
return false; /* held by someone else */
else if (whole == bdev)
return true; /* is a whole device which isn't held */
else if (whole->bd_holder == bd_may_claim)
return true; /* is a partition of a device that is being partitioned */
else if (whole->bd_holder != NULL)
return false; /* is a partition of a held device */
else
return true; /* is a partition of an un-held device */
}
/**
* bd_prepare_to_claim - prepare to claim a block device
* @bdev: block device of interest
* @whole: the whole device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Prepare to claim @bdev. This function fails if @bdev is already
* claimed by another holder and waits if another claiming is in
* progress. This function doesn't actually claim. On successful
* return, the caller has ownership of bd_claiming and bd_holder[s].
*
* CONTEXT:
* spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
* it multiple times.
*
* RETURNS:
* 0 if @bdev can be claimed, -EBUSY otherwise.
*/
static int bd_prepare_to_claim(struct block_device *bdev,
struct block_device *whole, void *holder)
{
retry:
/* if someone else claimed, fail */
if (!bd_may_claim(bdev, whole, holder))
return -EBUSY;
/* if claiming is already in progress, wait for it to finish */
if (whole->bd_claiming) {
wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
DEFINE_WAIT(wait);
prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&bdev_lock);
schedule();
finish_wait(wq, &wait);
spin_lock(&bdev_lock);
goto retry;
}
/* yay, all mine */
return 0;
}
/**
* bd_start_claiming - start claiming a block device
* @bdev: block device of interest
* @holder: holder trying to claim @bdev
*
* @bdev is about to be opened exclusively. Check @bdev can be opened
* exclusively and mark that an exclusive open is in progress. Each
* successful call to this function must be matched with a call to
* either bd_finish_claiming() or bd_abort_claiming() (which do not
* fail).
*
* This function is used to gain exclusive access to the block device
* without actually causing other exclusive open attempts to fail. It
* should be used when the open sequence itself requires exclusive
* access but may subsequently fail.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* Pointer to the block device containing @bdev on success, ERR_PTR()
* value on failure.
*/
static struct block_device *bd_start_claiming(struct block_device *bdev,
void *holder)
{
struct gendisk *disk;
struct block_device *whole;
int partno, err;
might_sleep();
/*
* @bdev might not have been initialized properly yet, look up
* and grab the outer block device the hard way.
*/
disk = get_gendisk(bdev->bd_dev, &partno);
if (!disk)
return ERR_PTR(-ENXIO);
/*
* Normally, @bdev should equal what's returned from bdget_disk()
* if partno is 0; however, some drivers (floppy) use multiple
* bdev's for the same physical device and @bdev may be one of the
* aliases. Keep @bdev if partno is 0. This means claimer
* tracking is broken for those devices but it has always been that
* way.
*/
if (partno)
whole = bdget_disk(disk, 0);
else
whole = bdgrab(bdev);
module_put(disk->fops->owner);
put_disk(disk);
if (!whole)
return ERR_PTR(-ENOMEM);
/* prepare to claim, if successful, mark claiming in progress */
spin_lock(&bdev_lock);
err = bd_prepare_to_claim(bdev, whole, holder);
if (err == 0) {
whole->bd_claiming = holder;
spin_unlock(&bdev_lock);
return whole;
} else {
spin_unlock(&bdev_lock);
bdput(whole);
return ERR_PTR(err);
}
}
#ifdef CONFIG_SYSFS
struct bd_holder_disk {
struct list_head list;
struct gendisk *disk;
int refcnt;
};
static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
struct gendisk *disk)
{
struct bd_holder_disk *holder;
list_for_each_entry(holder, &bdev->bd_holder_disks, list)
if (holder->disk == disk)
return holder;
return NULL;
}
static int add_symlink(struct kobject *from, struct kobject *to)
{
return sysfs_create_link(from, to, kobject_name(to));
}
static void del_symlink(struct kobject *from, struct kobject *to)
{
sysfs_remove_link(from, kobject_name(to));
}
/**
* bd_link_disk_holder - create symlinks between holding disk and slave bdev
* @bdev: the claimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* This functions creates the following sysfs symlinks.
*
* - from "slaves" directory of the holder @disk to the claimed @bdev
* - from "holders" directory of the @bdev to the holder @disk
*
* For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
* passed to bd_link_disk_holder(), then:
*
* /sys/block/dm-0/slaves/sda --> /sys/block/sda
* /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
*
* The caller must have claimed @bdev before calling this function and
* ensure that both @bdev and @disk are valid during the creation and
* lifetime of these symlinks.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
int ret = 0;
mutex_lock(&bdev->bd_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
/* FIXME: remove the following once add_disk() handles errors */
if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
goto out_unlock;
holder = bd_find_holder_disk(bdev, disk);
if (holder) {
holder->refcnt++;
goto out_unlock;
}
holder = kzalloc(sizeof(*holder), GFP_KERNEL);
if (!holder) {
ret = -ENOMEM;
goto out_unlock;
}
INIT_LIST_HEAD(&holder->list);
holder->disk = disk;
holder->refcnt = 1;
ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
if (ret)
goto out_free;
ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
if (ret)
goto out_del;
/*
* bdev could be deleted beneath us which would implicitly destroy
* the holder directory. Hold on to it.
*/
kobject_get(bdev->bd_part->holder_dir);
list_add(&holder->list, &bdev->bd_holder_disks);
goto out_unlock;
out_del:
del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
out_free:
kfree(holder);
out_unlock:
mutex_unlock(&bdev->bd_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
/**
* bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
* @bdev: the calimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* CONTEXT:
* Might sleep.
*/
void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
mutex_lock(&bdev->bd_mutex);
holder = bd_find_holder_disk(bdev, disk);
if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
del_symlink(bdev->bd_part->holder_dir,
&disk_to_dev(disk)->kobj);
kobject_put(bdev->bd_part->holder_dir);
list_del_init(&holder->list);
kfree(holder);
}
mutex_unlock(&bdev->bd_mutex);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
#endif
/**
* flush_disk - invalidates all buffer-cache entries on a disk
*
* @bdev: struct block device to be flushed
* @kill_dirty: flag to guide handling of dirty inodes
*
* Invalidates all buffer-cache entries on a disk. It should be called
* when a disk has been changed -- either by a media change or online
* resize.
*/
static void flush_disk(struct block_device *bdev, bool kill_dirty)
{
if (__invalidate_device(bdev, kill_dirty)) {
printk(KERN_WARNING "VFS: busy inodes on changed media or "
"resized disk %s\n",
bdev->bd_disk ? bdev->bd_disk->disk_name : "");
}
if (!bdev->bd_disk)
return;
if (disk_part_scan_enabled(bdev->bd_disk))
bdev->bd_invalidated = 1;
}
/**
* check_disk_size_change - checks for disk size change and adjusts bdev size.
* @disk: struct gendisk to check
* @bdev: struct bdev to adjust.
*
* This routine checks to see if the bdev size does not match the disk size
* and adjusts it if it differs.
*/
void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
{
loff_t disk_size, bdev_size;
disk_size = (loff_t)get_capacity(disk) << 9;
bdev_size = i_size_read(bdev->bd_inode);
if (disk_size != bdev_size) {
printk(KERN_INFO
"%s: detected capacity change from %lld to %lld\n",
disk->disk_name, bdev_size, disk_size);
i_size_write(bdev->bd_inode, disk_size);
flush_disk(bdev, false);
}
}
EXPORT_SYMBOL(check_disk_size_change);
/**
* revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
* @disk: struct gendisk to be revalidated
*
* This routine is a wrapper for lower-level driver's revalidate_disk
* call-backs. It is used to do common pre and post operations needed
* for all revalidate_disk operations.
*/
int revalidate_disk(struct gendisk *disk)
{
struct block_device *bdev;
int ret = 0;
if (disk->fops->revalidate_disk)
ret = disk->fops->revalidate_disk(disk);
bdev = bdget_disk(disk, 0);
if (!bdev)
return ret;
mutex_lock(&bdev->bd_mutex);
check_disk_size_change(disk, bdev);
bdev->bd_invalidated = 0;
mutex_unlock(&bdev->bd_mutex);
bdput(bdev);
return ret;
}
EXPORT_SYMBOL(revalidate_disk);
/*
* This routine checks whether a removable media has been changed,
* and invalidates all buffer-cache-entries in that case. This
* is a relatively slow routine, so we have to try to minimize using
* it. Thus it is called only upon a 'mount' or 'open'. This
* is the best way of combining speed and utility, I think.
* People changing diskettes in the middle of an operation deserve
* to lose :-)
*/
int check_disk_change(struct block_device *bdev)
{
struct gendisk *disk = bdev->bd_disk;
const struct block_device_operations *bdops = disk->fops;
unsigned int events;
events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
DISK_EVENT_EJECT_REQUEST);
if (!(events & DISK_EVENT_MEDIA_CHANGE))
return 0;
flush_disk(bdev, true);
if (bdops->revalidate_disk)
bdops->revalidate_disk(bdev->bd_disk);
return 1;
}
EXPORT_SYMBOL(check_disk_change);
void bd_set_size(struct block_device *bdev, loff_t size)
{
unsigned bsize = bdev_logical_block_size(bdev);
inode_lock(bdev->bd_inode);
i_size_write(bdev->bd_inode, size);
inode_unlock(bdev->bd_inode);
while (bsize < PAGE_SIZE) {
if (size & bsize)
break;
bsize <<= 1;
}
bdev->bd_block_size = bsize;
bdev->bd_inode->i_blkbits = blksize_bits(bsize);
}
EXPORT_SYMBOL(bd_set_size);
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
/*
* bd_mutex locking:
*
* mutex_lock(part->bd_mutex)
* mutex_lock_nested(whole->bd_mutex, 1)
*/
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
{
struct gendisk *disk;
struct module *owner;
int ret;
int partno;
int perm = 0;
if (mode & FMODE_READ)
perm |= MAY_READ;
if (mode & FMODE_WRITE)
perm |= MAY_WRITE;
/*
* hooks: /n/, see "layering violations".
*/
if (!for_part) {
ret = devcgroup_inode_permission(bdev->bd_inode, perm);
if (ret != 0) {
bdput(bdev);
return ret;
}
}
restart:
ret = -ENXIO;
disk = get_gendisk(bdev->bd_dev, &partno);
if (!disk)
goto out;
owner = disk->fops->owner;
disk_block_events(disk);
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (!bdev->bd_openers) {
bdev->bd_disk = disk;
bdev->bd_queue = disk->queue;
bdev->bd_contains = bdev;
if (!partno) {
ret = -ENXIO;
bdev->bd_part = disk_get_part(disk, partno);
if (!bdev->bd_part)
goto out_clear;
ret = 0;
if (disk->fops->open) {
ret = disk->fops->open(bdev, mode);
if (ret == -ERESTARTSYS) {
/* Lost a race with 'disk' being
* deleted, try again.
* See md.c
*/
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
bdev->bd_disk = NULL;
bdev->bd_queue = NULL;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
put_disk(disk);
module_put(owner);
goto restart;
}
}
if (!ret)
bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
/*
* If the device is invalidated, rescan partition
* if open succeeded or failed with -ENOMEDIUM.
* The latter is necessary to prevent ghost
* partitions on a removed medium.
*/
if (bdev->bd_invalidated) {
if (!ret)
rescan_partitions(disk, bdev);
else if (ret == -ENOMEDIUM)
invalidate_partitions(disk, bdev);
}
if (ret)
goto out_clear;
} else {
struct block_device *whole;
whole = bdget_disk(disk, 0);
ret = -ENOMEM;
if (!whole)
goto out_clear;
BUG_ON(for_part);
ret = __blkdev_get(whole, mode, 1);
if (ret)
goto out_clear;
bdev->bd_contains = whole;
bdev->bd_part = disk_get_part(disk, partno);
if (!(disk->flags & GENHD_FL_UP) ||
!bdev->bd_part || !bdev->bd_part->nr_sects) {
ret = -ENXIO;
goto out_clear;
}
bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
}
if (bdev->bd_bdi == &noop_backing_dev_info)
bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
} else {
if (bdev->bd_contains == bdev) {
ret = 0;
if (bdev->bd_disk->fops->open)
ret = bdev->bd_disk->fops->open(bdev, mode);
/* the same as first opener case, read comment there */
if (bdev->bd_invalidated) {
if (!ret)
rescan_partitions(bdev->bd_disk, bdev);
else if (ret == -ENOMEDIUM)
invalidate_partitions(bdev->bd_disk, bdev);
}
if (ret)
goto out_unlock_bdev;
}
/* only one opener holds refs to the module and disk */
put_disk(disk);
module_put(owner);
}
bdev->bd_openers++;
if (for_part)
bdev->bd_part_count++;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
return 0;
out_clear:
disk_put_part(bdev->bd_part);
bdev->bd_disk = NULL;
bdev->bd_part = NULL;
bdev->bd_queue = NULL;
if (bdev != bdev->bd_contains)
__blkdev_put(bdev->bd_contains, mode, 1);
bdev->bd_contains = NULL;
out_unlock_bdev:
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
put_disk(disk);
module_put(owner);
out:
bdput(bdev);
return ret;
}
/**
* blkdev_get - open a block device
* @bdev: block_device to open
* @mode: FMODE_* mask
* @holder: exclusive holder identifier
*
* Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
* open with exclusive access. Specifying %FMODE_EXCL with %NULL
* @holder is invalid. Exclusive opens may nest for the same @holder.
*
* On success, the reference count of @bdev is unchanged. On failure,
* @bdev is put.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
{
struct block_device *whole = NULL;
int res;
WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
if ((mode & FMODE_EXCL) && holder) {
whole = bd_start_claiming(bdev, holder);
if (IS_ERR(whole)) {
bdput(bdev);
return PTR_ERR(whole);
}
}
res = __blkdev_get(bdev, mode, 0);
if (whole) {
struct gendisk *disk = whole->bd_disk;
/* finish claiming */
mutex_lock(&bdev->bd_mutex);
spin_lock(&bdev_lock);
if (!res) {
BUG_ON(!bd_may_claim(bdev, whole, holder));
/*
* Note that for a whole device bd_holders
* will be incremented twice, and bd_holder
* will be set to bd_may_claim before being
* set to holder
*/
whole->bd_holders++;
whole->bd_holder = bd_may_claim;
bdev->bd_holders++;
bdev->bd_holder = holder;
}
/* tell others that we're done */
BUG_ON(whole->bd_claiming != holder);
whole->bd_claiming = NULL;
wake_up_bit(&whole->bd_claiming, 0);
spin_unlock(&bdev_lock);
/*
* Block event polling for write claims if requested. Any
* write holder makes the write_holder state stick until
* all are released. This is good enough and tracking
* individual writeable reference is too fragile given the
* way @mode is used in blkdev_get/put().
*/
if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
(disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
bdev->bd_write_holder = true;
disk_block_events(disk);
}
mutex_unlock(&bdev->bd_mutex);
bdput(whole);
}
return res;
}
EXPORT_SYMBOL(blkdev_get);
/**
* blkdev_get_by_path - open a block device by name
* @path: path to the block device to open
* @mode: FMODE_* mask
* @holder: exclusive holder identifier
*
* Open the blockdevice described by the device file at @path. @mode
* and @holder are identical to blkdev_get().
*
* On success, the returned block_device has reference count of one.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* Pointer to block_device on success, ERR_PTR(-errno) on failure.
*/
struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
void *holder)
{
struct block_device *bdev;
int err;
bdev = lookup_bdev(path);
if (IS_ERR(bdev))
return bdev;
err = blkdev_get(bdev, mode, holder);
if (err)
return ERR_PTR(err);
if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
blkdev_put(bdev, mode);
return ERR_PTR(-EACCES);
}
return bdev;
}
EXPORT_SYMBOL(blkdev_get_by_path);
/**
* blkdev_get_by_dev - open a block device by device number
* @dev: device number of block device to open
* @mode: FMODE_* mask
* @holder: exclusive holder identifier
*
* Open the blockdevice described by device number @dev. @mode and
* @holder are identical to blkdev_get().
*
* Use it ONLY if you really do not have anything better - i.e. when
* you are behind a truly sucky interface and all you are given is a
* device number. _Never_ to be used for internal purposes. If you
* ever need it - reconsider your API.
*
* On success, the returned block_device has reference count of one.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* Pointer to block_device on success, ERR_PTR(-errno) on failure.
*/
struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
{
struct block_device *bdev;
int err;
bdev = bdget(dev);
if (!bdev)
return ERR_PTR(-ENOMEM);
err = blkdev_get(bdev, mode, holder);
if (err)
return ERR_PTR(err);
return bdev;
}
EXPORT_SYMBOL(blkdev_get_by_dev);
static int blkdev_open(struct inode * inode, struct file * filp)
{
struct block_device *bdev;
/*
* Preserve backwards compatibility and allow large file access
* even if userspace doesn't ask for it explicitly. Some mkfs
* binary needs it. We might want to drop this workaround
* during an unstable branch.
*/
filp->f_flags |= O_LARGEFILE;
if (filp->f_flags & O_NDELAY)
filp->f_mode |= FMODE_NDELAY;
if (filp->f_flags & O_EXCL)
filp->f_mode |= FMODE_EXCL;
if ((filp->f_flags & O_ACCMODE) == 3)
filp->f_mode |= FMODE_WRITE_IOCTL;
bdev = bd_acquire(inode);
if (bdev == NULL)
return -ENOMEM;
filp->f_mapping = bdev->bd_inode->i_mapping;
filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
return blkdev_get(bdev, filp->f_mode, filp);
}
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
{
struct gendisk *disk = bdev->bd_disk;
struct block_device *victim = NULL;
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (for_part)
bdev->bd_part_count--;
if (!--bdev->bd_openers) {
WARN_ON_ONCE(bdev->bd_holders);
sync_blockdev(bdev);
kill_bdev(bdev);
bdev_write_inode(bdev);
}
if (bdev->bd_contains == bdev) {
if (disk->fops->release)
disk->fops->release(disk, mode);
}
if (!bdev->bd_openers) {
struct module *owner = disk->fops->owner;
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
bdev->bd_disk = NULL;
if (bdev != bdev->bd_contains)
victim = bdev->bd_contains;
bdev->bd_contains = NULL;
put_disk(disk);
module_put(owner);
}
mutex_unlock(&bdev->bd_mutex);
bdput(bdev);
if (victim)
__blkdev_put(victim, mode, 1);
}
void blkdev_put(struct block_device *bdev, fmode_t mode)
{
mutex_lock(&bdev->bd_mutex);
if (mode & FMODE_EXCL) {
bool bdev_free;
/*
* Release a claim on the device. The holder fields
* are protected with bdev_lock. bd_mutex is to
* synchronize disk_holder unlinking.
*/
spin_lock(&bdev_lock);
WARN_ON_ONCE(--bdev->bd_holders < 0);
WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
/* bd_contains might point to self, check in a separate step */
if ((bdev_free = !bdev->bd_holders))
bdev->bd_holder = NULL;
if (!bdev->bd_contains->bd_holders)
bdev->bd_contains->bd_holder = NULL;
spin_unlock(&bdev_lock);
/*
* If this was the last claim, remove holder link and
* unblock evpoll if it was a write holder.
*/
if (bdev_free && bdev->bd_write_holder) {
disk_unblock_events(bdev->bd_disk);
bdev->bd_write_holder = false;
}
}
/*
* Trigger event checking and tell drivers to flush MEDIA_CHANGE
* event. This is to ensure detection of media removal commanded
* from userland - e.g. eject(1).
*/
disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
mutex_unlock(&bdev->bd_mutex);
__blkdev_put(bdev, mode, 0);
}
EXPORT_SYMBOL(blkdev_put);
static int blkdev_close(struct inode * inode, struct file * filp)
{
struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
blkdev_put(bdev, filp->f_mode);
return 0;
}
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
{
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
fmode_t mode = file->f_mode;
/*
* O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
* to updated it before every ioctl.
*/
if (file->f_flags & O_NDELAY)
mode |= FMODE_NDELAY;
else
mode &= ~FMODE_NDELAY;
return blkdev_ioctl(bdev, mode, cmd, arg);
}
/*
* Write data to the block device. Only intended for the block device itself
* and the raw driver which basically is a fake block device.
*
* Does not take i_mutex for the write and thus is not for general purpose
* use.
*/
ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
struct blk_plug plug;
ssize_t ret;
if (bdev_read_only(I_BDEV(bd_inode)))
return -EPERM;
if (!iov_iter_count(from))
return 0;
if (iocb->ki_pos >= size)
return -ENOSPC;
iov_iter_truncate(from, size - iocb->ki_pos);
blk_start_plug(&plug);
ret = __generic_file_write_iter(iocb, from);
if (ret > 0)
ret = generic_write_sync(iocb, ret);
blk_finish_plug(&plug);
return ret;
}
EXPORT_SYMBOL_GPL(blkdev_write_iter);
ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
loff_t pos = iocb->ki_pos;
if (pos >= size)
return 0;
size -= pos;
iov_iter_truncate(to, size);
return generic_file_read_iter(iocb, to);
}
EXPORT_SYMBOL_GPL(blkdev_read_iter);
/*
* Try to release a page associated with block device when the system
* is under memory pressure.
*/
static int blkdev_releasepage(struct page *page, gfp_t wait)
{
struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
if (super && super->s_op->bdev_try_to_free_page)
return super->s_op->bdev_try_to_free_page(super, page, wait);
return try_to_free_buffers(page);
}
static int blkdev_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
if (dax_mapping(mapping)) {
struct block_device *bdev = I_BDEV(mapping->host);
return dax_writeback_mapping_range(mapping, bdev, wbc);
}
return generic_writepages(mapping, wbc);
}
static const struct address_space_operations def_blk_aops = {
.readpage = blkdev_readpage,
.readpages = blkdev_readpages,
.writepage = blkdev_writepage,
.write_begin = blkdev_write_begin,
.write_end = blkdev_write_end,
.writepages = blkdev_writepages,
.releasepage = blkdev_releasepage,
.direct_IO = blkdev_direct_IO,
.is_dirty_writeback = buffer_check_dirty_writeback,
};
#define BLKDEV_FALLOC_FL_SUPPORTED \
(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
static long blkdev_fallocate(struct file *file, int mode, loff_t start,
loff_t len)
{
struct block_device *bdev = I_BDEV(bdev_file_inode(file));
struct address_space *mapping;
loff_t end = start + len - 1;
loff_t isize;
int error;
/* Fail if we don't recognize the flags. */
if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
return -EOPNOTSUPP;
/* Don't go off the end of the device. */
isize = i_size_read(bdev->bd_inode);
if (start >= isize)
return -EINVAL;
if (end >= isize) {
if (mode & FALLOC_FL_KEEP_SIZE) {
len = isize - start;
end = start + len - 1;
} else
return -EINVAL;
}
/*
* Don't allow IO that isn't aligned to logical block size.
*/
if ((start | len) & (bdev_logical_block_size(bdev) - 1))
return -EINVAL;
/* Invalidate the page cache, including dirty pages. */
mapping = bdev->bd_inode->i_mapping;
truncate_inode_pages_range(mapping, start, end);
switch (mode) {
case FALLOC_FL_ZERO_RANGE:
case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
break;
case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
break;
case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
GFP_KERNEL, 0);
break;
default:
return -EOPNOTSUPP;
}
if (error)
return error;
/*
* Invalidate again; if someone wandered in and dirtied a page,
* the caller will be given -EBUSY. The third argument is
* inclusive, so the rounding here is safe.
*/
return invalidate_inode_pages2_range(mapping,
start >> PAGE_SHIFT,
end >> PAGE_SHIFT);
}
const struct file_operations def_blk_fops = {
.open = blkdev_open,
.release = blkdev_close,
.llseek = block_llseek,
.read_iter = blkdev_read_iter,
.write_iter = blkdev_write_iter,
.mmap = generic_file_mmap,
.fsync = blkdev_fsync,
.unlocked_ioctl = block_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = compat_blkdev_ioctl,
#endif
.splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.fallocate = blkdev_fallocate,
};
int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
{
int res;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
res = blkdev_ioctl(bdev, 0, cmd, arg);
set_fs(old_fs);
return res;
}
EXPORT_SYMBOL(ioctl_by_bdev);
/**
* lookup_bdev - lookup a struct block_device by name
* @pathname: special file representing the block device
*
* Get a reference to the blockdevice at @pathname in the current
* namespace if possible and return it. Return ERR_PTR(error)
* otherwise.
*/
struct block_device *lookup_bdev(const char *pathname)
{
struct block_device *bdev;
struct inode *inode;
struct path path;
int error;
if (!pathname || !*pathname)
return ERR_PTR(-EINVAL);
error = kern_path(pathname, LOOKUP_FOLLOW, &path);
if (error)
return ERR_PTR(error);
inode = d_backing_inode(path.dentry);
error = -ENOTBLK;
if (!S_ISBLK(inode->i_mode))
goto fail;
error = -EACCES;
if (!may_open_dev(&path))
goto fail;
error = -ENOMEM;
bdev = bd_acquire(inode);
if (!bdev)
goto fail;
out:
path_put(&path);
return bdev;
fail:
bdev = ERR_PTR(error);
goto out;
}
EXPORT_SYMBOL(lookup_bdev);
int __invalidate_device(struct block_device *bdev, bool kill_dirty)
{
struct super_block *sb = get_super(bdev);
int res = 0;
if (sb) {
/*
* no need to lock the super, get_super holds the
* read mutex so the filesystem cannot go away
* under us (->put_super runs with the write lock
* hold).
*/
shrink_dcache_sb(sb);
res = invalidate_inodes(sb, kill_dirty);
drop_super(sb);
}
invalidate_bdev(bdev);
return res;
}
EXPORT_SYMBOL(__invalidate_device);
void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
{
struct inode *inode, *old_inode = NULL;
spin_lock(&blockdev_superblock->s_inode_list_lock);
list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
struct address_space *mapping = inode->i_mapping;
struct block_device *bdev;
spin_lock(&inode->i_lock);
if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
mapping->nrpages == 0) {
spin_unlock(&inode->i_lock);
continue;
}
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&blockdev_superblock->s_inode_list_lock);
/*
* We hold a reference to 'inode' so it couldn't have been
* removed from s_inodes list while we dropped the
* s_inode_list_lock We cannot iput the inode now as we can
* be holding the last reference and we cannot iput it under
* s_inode_list_lock. So we keep the reference and iput it
* later.
*/
iput(old_inode);
old_inode = inode;
bdev = I_BDEV(inode);
mutex_lock(&bdev->bd_mutex);
if (bdev->bd_openers)
func(bdev, arg);
mutex_unlock(&bdev->bd_mutex);
spin_lock(&blockdev_superblock->s_inode_list_lock);
}
spin_unlock(&blockdev_superblock->s_inode_list_lock);
iput(old_inode);
}