mm/xip: share the i_mmap_rwsem
__xip_unmap() will remove the xip sparse page from the cache and take down pte mapping, without altering the interval tree, thus share the i_mmap_rwsem when searching for the ptes to unmap. Additionally, tidy up the function a bit and make variables only local to the interval tree walk loop. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -155,22 +155,14 @@ xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
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EXPORT_SYMBOL_GPL(xip_file_read);
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/*
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* __xip_unmap is invoked from xip_unmap and
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* xip_write
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* __xip_unmap is invoked from xip_unmap and xip_write
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*
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* This function walks all vmas of the address_space and unmaps the
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* __xip_sparse_page when found at pgoff.
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*/
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static void
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__xip_unmap (struct address_space * mapping,
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unsigned long pgoff)
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static void __xip_unmap(struct address_space * mapping, unsigned long pgoff)
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{
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struct vm_area_struct *vma;
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struct mm_struct *mm;
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unsigned long address;
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pte_t *pte;
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pte_t pteval;
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spinlock_t *ptl;
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struct page *page;
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unsigned count;
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int locked = 0;
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@ -182,11 +174,14 @@ __xip_unmap (struct address_space * mapping,
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return;
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retry:
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i_mmap_lock_write(mapping);
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i_mmap_lock_read(mapping);
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vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
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mm = vma->vm_mm;
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address = vma->vm_start +
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pte_t *pte, pteval;
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spinlock_t *ptl;
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struct mm_struct *mm = vma->vm_mm;
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unsigned long address = vma->vm_start +
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((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
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BUG_ON(address < vma->vm_start || address >= vma->vm_end);
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pte = page_check_address(page, mm, address, &ptl, 1);
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if (pte) {
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@ -202,7 +197,7 @@ retry:
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page_cache_release(page);
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}
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}
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i_mmap_unlock_write(mapping);
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i_mmap_unlock_read(mapping);
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if (locked) {
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mutex_unlock(&xip_sparse_mutex);
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