| Message ID | 20240123-vfs-bdev-file-v2-32-adbd023e19cc@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Open block devices as files | expand |
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
On Tue 23-01-24 14:26:49, Christian Brauner wrote: > We just need to use the holder to indicate whether a block device open > was exclusive or not. We did use to do that before but had to give that > up once we switched to struct bdev_handle. Before struct bdev_handle we > only stashed stuff in file->private_data if this was an exclusive open > but after struct bdev_handle we always set file->private_data to a > struct bdev_handle and so we had to use bdev_handle->mode or > bdev_handle->holder. Now that we don't use struct bdev_handle anymore we > can revert back to the old behavior. > > Signed-off-by: Christian Brauner <brauner@kernel.org> Two small comments below. > diff --git a/block/fops.c b/block/fops.c > index f56bdfe459de..a0bff2c0d88d 100644 > --- a/block/fops.c > +++ b/block/fops.c > @@ -569,7 +569,6 @@ static int blkdev_fsync(struct file *filp, loff_t start, loff_t end, > blk_mode_t file_to_blk_mode(struct file *file) > { > blk_mode_t mode = 0; > - struct bdev_handle *handle = file->private_data; > > if (file->f_mode & FMODE_READ) > mode |= BLK_OPEN_READ; > @@ -579,8 +578,8 @@ blk_mode_t file_to_blk_mode(struct file *file) > * do_dentry_open() clears O_EXCL from f_flags, use handle->mode to > * determine whether the open was exclusive for already open files. > */ ^^^ This comment needs update now... > - if (handle) > - mode |= handle->mode & BLK_OPEN_EXCL; > + if (file->private_data) > + mode |= BLK_OPEN_EXCL; > else if (file->f_flags & O_EXCL) > mode |= BLK_OPEN_EXCL; > if (file->f_flags & O_NDELAY) > @@ -601,12 +600,17 @@ static int blkdev_open(struct inode *inode, struct file *filp) > { > struct block_device *bdev; > blk_mode_t mode; > - void *holder; > int ret; > > + /* > + * Use the file private data to store the holder for exclusive opens. > + * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL. > + */ > + if (filp->f_flags & O_EXCL) > + filp->private_data = filp; Well, if we have O_EXCL in f_flags here, then file_to_blk_mode() on the next line is going to do the right thing and set BLK_OPEN_EXCL even without filp->private_data. So this shound't be needed AFAICT. > mode = file_to_blk_mode(filp); > - holder = mode & BLK_OPEN_EXCL ? filp : NULL; > - ret = bdev_permission(inode->i_rdev, mode, holder); > + ret = bdev_permission(inode->i_rdev, mode, filp->private_data); > if (ret) > return ret; Honza
On Thu, Feb 01, 2024 at 12:20:08PM +0100, Jan Kara wrote: > On Tue 23-01-24 14:26:49, Christian Brauner wrote: > > We just need to use the holder to indicate whether a block device open > > was exclusive or not. We did use to do that before but had to give that > > up once we switched to struct bdev_handle. Before struct bdev_handle we > > only stashed stuff in file->private_data if this was an exclusive open > > but after struct bdev_handle we always set file->private_data to a > > struct bdev_handle and so we had to use bdev_handle->mode or > > bdev_handle->holder. Now that we don't use struct bdev_handle anymore we > > can revert back to the old behavior. > > > > Signed-off-by: Christian Brauner <brauner@kernel.org> > > Two small comments below. > > > diff --git a/block/fops.c b/block/fops.c > > index f56bdfe459de..a0bff2c0d88d 100644 > > --- a/block/fops.c > > +++ b/block/fops.c > > @@ -569,7 +569,6 @@ static int blkdev_fsync(struct file *filp, loff_t start, loff_t end, > > blk_mode_t file_to_blk_mode(struct file *file) > > { > > blk_mode_t mode = 0; > > - struct bdev_handle *handle = file->private_data; > > > > if (file->f_mode & FMODE_READ) > > mode |= BLK_OPEN_READ; > > @@ -579,8 +578,8 @@ blk_mode_t file_to_blk_mode(struct file *file) > > * do_dentry_open() clears O_EXCL from f_flags, use handle->mode to > > * determine whether the open was exclusive for already open files. > > */ > ^^^ This comment needs update now... > > > - if (handle) > > - mode |= handle->mode & BLK_OPEN_EXCL; > > + if (file->private_data) > > + mode |= BLK_OPEN_EXCL; > > else if (file->f_flags & O_EXCL) > > mode |= BLK_OPEN_EXCL; > > if (file->f_flags & O_NDELAY) > > @@ -601,12 +600,17 @@ static int blkdev_open(struct inode *inode, struct file *filp) > > { > > struct block_device *bdev; > > blk_mode_t mode; > > - void *holder; > > int ret; > > > > + /* > > + * Use the file private data to store the holder for exclusive opens. > > + * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL. > > + */ > > + if (filp->f_flags & O_EXCL) > > + filp->private_data = filp; > > Well, if we have O_EXCL in f_flags here, then file_to_blk_mode() on the > next line is going to do the right thing and set BLK_OPEN_EXCL even > without filp->private_data. So this shound't be needed AFAICT. Fixed.
diff --git a/block/bdev.c b/block/bdev.c index 9d96a43f198d..4b47003d8082 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -799,7 +799,7 @@ static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) bdev->bd_writers++; } -static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode) +static void bdev_yield_write_access(struct file *bdev_file) { struct block_device *bdev; @@ -810,7 +810,7 @@ static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode) /* Yield exclusive or shared write access. */ if (bdev_file->f_op == &def_blk_fops_restricted) bdev_unblock_writes(bdev); - else if (mode & BLK_OPEN_WRITE) + else if (bdev_file->f_mode & FMODE_WRITE) bdev->bd_writers--; } @@ -838,16 +838,10 @@ static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode) int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder, const struct blk_holder_ops *hops, struct file *bdev_file) { - struct bdev_handle *handle = kmalloc(sizeof(struct bdev_handle), - GFP_KERNEL); bool unblock_events = true; struct gendisk *disk = bdev->bd_disk; int ret; - handle = kmalloc(sizeof(struct bdev_handle), GFP_KERNEL); - if (!handle) - return -ENOMEM; - if (holder) { mode |= BLK_OPEN_EXCL; ret = bd_prepare_to_claim(bdev, holder, hops); @@ -896,8 +890,6 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder, if (unblock_events) disk_unblock_events(disk); - handle->holder = holder; - handle->mode = mode; /* * Preserve backwards compatibility and allow large file access @@ -911,7 +903,7 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder, bdev_file->f_mode |= FMODE_NOWAIT; bdev_file->f_mapping = bdev->bd_inode->i_mapping; bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping); - bdev_file->private_data = handle; + bdev_file->private_data = holder; return 0; put_module: @@ -921,7 +913,6 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder, bd_abort_claiming(bdev, holder); mutex_unlock(&disk->open_mutex); disk_unblock_events(disk); - kfree(handle); return ret; } @@ -1027,7 +1018,7 @@ EXPORT_SYMBOL(bdev_file_open_by_path); void bdev_release(struct file *bdev_file) { struct block_device *bdev = file_bdev(bdev_file); - struct bdev_handle *handle = bdev_file->private_data; + void *holder = bdev_file->private_data; struct gendisk *disk = bdev->bd_disk; /* @@ -1041,10 +1032,10 @@ void bdev_release(struct file *bdev_file) sync_blockdev(bdev); mutex_lock(&disk->open_mutex); - bdev_yield_write_access(bdev_file, handle->mode); + bdev_yield_write_access(bdev_file); - if (handle->holder) - bd_end_claim(bdev, handle->holder); + if (holder) + bd_end_claim(bdev, holder); /* * Trigger event checking and tell drivers to flush MEDIA_CHANGE @@ -1061,7 +1052,6 @@ void bdev_release(struct file *bdev_file) module_put(disk->fops->owner); blkdev_put_no_open(bdev); - kfree(handle); } /** diff --git a/block/blk.h b/block/blk.h index dfa958909c54..cce1ac0ff303 100644 --- a/block/blk.h +++ b/block/blk.h @@ -27,11 +27,6 @@ struct blk_flush_queue { struct request *flush_rq; }; -struct bdev_handle { - void *holder; - blk_mode_t mode; -}; - bool is_flush_rq(struct request *req); struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size, diff --git a/block/fops.c b/block/fops.c index f56bdfe459de..a0bff2c0d88d 100644 --- a/block/fops.c +++ b/block/fops.c @@ -569,7 +569,6 @@ static int blkdev_fsync(struct file *filp, loff_t start, loff_t end, blk_mode_t file_to_blk_mode(struct file *file) { blk_mode_t mode = 0; - struct bdev_handle *handle = file->private_data; if (file->f_mode & FMODE_READ) mode |= BLK_OPEN_READ; @@ -579,8 +578,8 @@ blk_mode_t file_to_blk_mode(struct file *file) * do_dentry_open() clears O_EXCL from f_flags, use handle->mode to * determine whether the open was exclusive for already open files. */ - if (handle) - mode |= handle->mode & BLK_OPEN_EXCL; + if (file->private_data) + mode |= BLK_OPEN_EXCL; else if (file->f_flags & O_EXCL) mode |= BLK_OPEN_EXCL; if (file->f_flags & O_NDELAY) @@ -601,12 +600,17 @@ static int blkdev_open(struct inode *inode, struct file *filp) { struct block_device *bdev; blk_mode_t mode; - void *holder; int ret; + /* + * Use the file private data to store the holder for exclusive opens. + * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL. + */ + if (filp->f_flags & O_EXCL) + filp->private_data = filp; + mode = file_to_blk_mode(filp); - holder = mode & BLK_OPEN_EXCL ? filp : NULL; - ret = bdev_permission(inode->i_rdev, mode, holder); + ret = bdev_permission(inode->i_rdev, mode, filp->private_data); if (ret) return ret; @@ -614,7 +618,7 @@ static int blkdev_open(struct inode *inode, struct file *filp) if (!bdev) return -ENXIO; - ret = bdev_open(bdev, mode, holder, NULL, filp); + ret = bdev_open(bdev, mode, filp->private_data, NULL, filp); if (ret) blkdev_put_no_open(bdev); return ret;
We just need to use the holder to indicate whether a block device open was exclusive or not. We did use to do that before but had to give that up once we switched to struct bdev_handle. Before struct bdev_handle we only stashed stuff in file->private_data if this was an exclusive open but after struct bdev_handle we always set file->private_data to a struct bdev_handle and so we had to use bdev_handle->mode or bdev_handle->holder. Now that we don't use struct bdev_handle anymore we can revert back to the old behavior. Signed-off-by: Christian Brauner <brauner@kernel.org> --- block/bdev.c | 24 +++++++----------------- block/blk.h | 5 ----- block/fops.c | 18 +++++++++++------- 3 files changed, 18 insertions(+), 29 deletions(-)