forked from Minki/linux
ext4: return to starting transaction in ext4_dax_huge_fault()
DAX will return to locking exceptional entry before mapping blocks for a
page fault to fix possible races with concurrent writes. To avoid lock
inversion between exceptional entry lock and transaction start, start
the transaction already in ext4_dax_huge_fault().
Fixes: 9f141d6ef6
Link: http://lkml.kernel.org/r/20170510085419.27601-4-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
cd656375f9
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fb26a1cbed
@ -257,6 +257,7 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf,
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enum page_entry_size pe_size)
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{
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int result;
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handle_t *handle = NULL;
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struct inode *inode = file_inode(vmf->vma->vm_file);
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struct super_block *sb = inode->i_sb;
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bool write = vmf->flags & FAULT_FLAG_WRITE;
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@ -264,12 +265,24 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf,
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if (write) {
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sb_start_pagefault(sb);
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file_update_time(vmf->vma->vm_file);
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down_read(&EXT4_I(inode)->i_mmap_sem);
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handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
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EXT4_DATA_TRANS_BLOCKS(sb));
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} else {
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down_read(&EXT4_I(inode)->i_mmap_sem);
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}
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down_read(&EXT4_I(inode)->i_mmap_sem);
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result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops);
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up_read(&EXT4_I(inode)->i_mmap_sem);
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if (write)
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if (!IS_ERR(handle))
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result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops);
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else
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result = VM_FAULT_SIGBUS;
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if (write) {
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if (!IS_ERR(handle))
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ext4_journal_stop(handle);
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up_read(&EXT4_I(inode)->i_mmap_sem);
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sb_end_pagefault(sb);
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} else {
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up_read(&EXT4_I(inode)->i_mmap_sem);
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}
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return result;
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}
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