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Commit 4d9a2c87 authored by Jan Kara's avatar Jan Kara Committed by Ross Zwisler
Browse files

dax: Remove i_mmap_lock protection 



Currently faults are protected against truncate by filesystem specific
i_mmap_sem and page lock in case of hole page. Cow faults are protected
DAX radix tree entry locking. So there's no need for i_mmap_lock in DAX
code. Remove it.

Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
parent bc2466e4

fs/dax.c

+5 −19
Original line number Diff line number Diff line
@@ -798,29 +798,19 @@ static int dax_insert_mapping(struct address_space *mapping, 
		.sector = to_sector(bh, mapping->host),

		.size = bh->b_size,

	};

	int error;

	void *ret;

	void *entry = *entryp;



	i_mmap_lock_read(mapping);



	if (dax_map_atomic(bdev, &dax) < 0) {

		error = PTR_ERR(dax.addr);

		goto out;

	}

	if (dax_map_atomic(bdev, &dax) < 0)

		return PTR_ERR(dax.addr);

	dax_unmap_atomic(bdev, &dax);



	ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector);

	if (IS_ERR(ret)) {

		error = PTR_ERR(ret);

		goto out;

	}

	if (IS_ERR(ret))

		return PTR_ERR(ret);

	*entryp = ret;



	error = vm_insert_mixed(vma, vaddr, dax.pfn);

 out:

	i_mmap_unlock_read(mapping);

	return error;

	return vm_insert_mixed(vma, vaddr, dax.pfn);

}



/**
@@ -1058,8 +1048,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, 
		truncate_pagecache_range(inode, lstart, lend);

	}



	i_mmap_lock_read(mapping);



	if (!write && !buffer_mapped(&bh)) {

		spinlock_t *ptl;

		pmd_t entry;
@@ -1148,8 +1136,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, 
	}



 out:

	i_mmap_unlock_read(mapping);



	return result;



 fallback:

mm/memory.c

+0 −2
Original line number Diff line number Diff line
@@ -2453,8 +2453,6 @@ void unmap_mapping_range(struct address_space *mapping, 
	if (details.last_index < details.first_index)

		details.last_index = ULONG_MAX;





	/* DAX uses i_mmap_lock to serialise file truncate vs page fault */

	i_mmap_lock_write(mapping);

	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))

		unmap_mapping_range_tree(&mapping->i_mmap, &details);