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| author | Dave Chinner <dchinner@redhat.com> | 2015-06-04 09:18:18 +1000 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2015-06-04 09:18:18 +1000 |
| commit | ce5c5d554dc47a4fb4360c84b72231fea081e7a0 (patch) | |
| tree | 93915bd75b2061c36dfbffd10a8efd22e0d7282b | |
| parent | e842f2903908934187af7232fb5b21da527d1757 (diff) | |
| download | linux-stable-ce5c5d554dc47a4fb4360c84b72231fea081e7a0.tar.gz linux-stable-ce5c5d554dc47a4fb4360c84b72231fea081e7a0.tar.bz2 linux-stable-ce5c5d554dc47a4fb4360c84b72231fea081e7a0.zip | |
dax: expose __dax_fault for filesystems with locking constraints
Some filesystems cannot call dax_fault() directly because they have
different locking and/or allocation constraints in the page fault IO
path. To handle this, we need to follow the same model as the
generic block_page_mkwrite code, where the internals are exposed via
__block_page_mkwrite() so that filesystems can wrap the correct
locking and operations around the outside.
This is loosely based on a patch originally from Matthew Willcox.
Unlike the original patch, it does not change ext4 code, error
returns or unwritten extent conversion handling. It also adds a
__dax_mkwrite() wrapper for .page_mkwrite implementations to do the
right thing, too.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>
| -rw-r--r-- | fs/dax.c | 15 | ||||
| -rw-r--r-- | include/linux/fs.h | 5 |
2 files changed, 17 insertions, 3 deletions
@@ -312,7 +312,17 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, return error; } -static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, +/** + * __dax_fault - handle a page fault on a DAX file + * @vma: The virtual memory area where the fault occurred + * @vmf: The description of the fault + * @get_block: The filesystem method used to translate file offsets to blocks + * + * When a page fault occurs, filesystems may call this helper in their + * fault handler for DAX files. __dax_fault() assumes the caller has done all + * the necessary locking for the page fault to proceed successfully. + */ +int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, get_block_t get_block, dax_iodone_t complete_unwritten) { struct file *file = vma->vm_file; @@ -443,6 +453,7 @@ static int do_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } goto out; } +EXPORT_SYMBOL(__dax_fault); /** * dax_fault - handle a page fault on a DAX file @@ -463,7 +474,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, sb_start_pagefault(sb); file_update_time(vma->vm_file); } - result = do_dax_fault(vma, vmf, get_block, complete_unwritten); + result = __dax_fault(vma, vmf, get_block, complete_unwritten); if (vmf->flags & FAULT_FLAG_WRITE) sb_end_pagefault(sb); diff --git a/include/linux/fs.h b/include/linux/fs.h index c9b4cca9e08d..5784377e7c56 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2630,8 +2630,11 @@ int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t); int dax_truncate_page(struct inode *, loff_t from, get_block_t); int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, dax_iodone_t); +int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, + dax_iodone_t); int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *); -#define dax_mkwrite(vma, vmf, gb, iod) dax_fault(vma, vmf, gb, iod) +#define dax_mkwrite(vma, vmf, gb, iod) dax_fault(vma, vmf, gb, iod) +#define __dax_mkwrite(vma, vmf, gb, iod) __dax_fault(vma, vmf, gb, iod) #ifdef CONFIG_BLOCK typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode, |