From eec38f5d86d27535509c99f02ccc642ceb0c3e2a Mon Sep 17 00:00:00 2001 From: John Groves Date: Fri, 27 Mar 2026 21:05:12 +0000 Subject: dax: Add fs_dax_get() func to prepare dax for fs-dax usage The fs_dax_get() function should be called by fs-dax file systems after opening a fsdev dax device. This adds holder_operations, which provides a memory failure callback path and effects exclusivity between callers of fs_dax_get(). fs_dax_get() is specific to fsdev_dax, so it checks the driver type (which required touching bus.[ch]). fs_dax_get() fails if fsdev_dax is not bound to the memory. This function serves the same role as fs_dax_get_by_bdev(), which dax file systems call after opening the pmem block device. This can't be located in fsdev.c because struct dax_device is opaque there. This will be called by fs/fuse/famfs.c in a subsequent commit. Reviewed-by: Jonathan Cameron Reviewed-by: Dave Jiang Signed-off-by: John Groves Link: https://patch.msgid.link/0100019d311d8750-75395c22-031b-4d5f-aebe-790dca656b87-000000@email.amazonses.com Signed-off-by: Ira Weiny --- include/linux/dax.h | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dax.h b/include/linux/dax.h index b19bfe0c2fd1..a85e270bfb3c 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -130,7 +130,6 @@ int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk); void dax_remove_host(struct gendisk *disk); struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off, void *holder, const struct dax_holder_operations *ops); -void fs_put_dax(struct dax_device *dax_dev, void *holder); #else static inline int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk) { @@ -145,12 +144,12 @@ static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, { return NULL; } -static inline void fs_put_dax(struct dax_device *dax_dev, void *holder) -{ -} #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */ #if IS_ENABLED(CONFIG_FS_DAX) +void fs_put_dax(struct dax_device *dax_dev, void *holder); +int fs_dax_get(struct dax_device *dax_dev, void *holder, + const struct dax_holder_operations *hops); int dax_writeback_mapping_range(struct address_space *mapping, struct dax_device *dax_dev, struct writeback_control *wbc); int dax_folio_reset_order(struct folio *folio); @@ -164,6 +163,15 @@ dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, void dax_unlock_mapping_entry(struct address_space *mapping, unsigned long index, dax_entry_t cookie); #else +static inline void fs_put_dax(struct dax_device *dax_dev, void *holder) +{ +} + +static inline int fs_dax_get(struct dax_device *dax_dev, void *holder, + const struct dax_holder_operations *hops) +{ + return -EOPNOTSUPP; +} static inline struct page *dax_layout_busy_page(struct address_space *mapping) { return NULL; -- cgit v1.2.3