The patch titled
Subject: ext4: start transaction before calling into DAX
has been removed from the -mm tree. Its filename was
ext4-start-transaction-before-calling-into-dax.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: ext4: start transaction before calling into DAX
Jan Kara pointed out that in the case where we are writing to a hole, we
can end up with a lock inversion between the page lock and the journal
lock. We can avoid this by starting the transaction in ext4 before
calling into DAX. The journal lock nests inside the superblock pagefault
lock, so we have to duplicate that code from dax_fault, like XFS does.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ext4/file.c | 55 ++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 52 insertions(+), 3 deletions(-)
diff -puN fs/ext4/file.c~ext4-start-transaction-before-calling-into-dax fs/ext4/file.c
--- a/fs/ext4/file.c~ext4-start-transaction-before-calling-into-dax
+++ a/fs/ext4/file.c
@@ -207,14 +207,63 @@ static void ext4_end_io_unwritten(struct
static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- return dax_fault(vma, vmf, ext4_get_block_dax, ext4_end_io_unwritten);
+ int result;
+ handle_t *handle = NULL;
+ struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
+
+ if (write) {
+ sb_start_pagefault(sb);
+ file_update_time(vma->vm_file);
+ handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
+ EXT4_DATA_TRANS_BLOCKS(sb));
+ }
+
+ if (IS_ERR(handle))
+ result = VM_FAULT_SIGBUS;
+ else
+ result = __dax_fault(vma, vmf, ext4_get_block_dax,
+ ext4_end_io_unwritten);
+
+ if (write) {
+ if (!IS_ERR(handle))
+ ext4_journal_stop(handle);
+ sb_end_pagefault(sb);
+ }
+
+ return result;
}
static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, unsigned int flags)
{
- return dax_pmd_fault(vma, addr, pmd, flags, ext4_get_block_dax,
- ext4_end_io_unwritten);
+ int result;
+ handle_t *handle = NULL;
+ struct inode *inode = file_inode(vma->vm_file);
+ struct super_block *sb = inode->i_sb;
+ bool write = flags & FAULT_FLAG_WRITE;
+
+ if (write) {
+ sb_start_pagefault(sb);
+ file_update_time(vma->vm_file);
+ handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
+ ext4_chunk_trans_blocks(inode,
+ PMD_SIZE / PAGE_SIZE));
+ }
+
+ if (IS_ERR(handle))
+ result = VM_FAULT_SIGBUS;
+ else
+ result = __dax_pmd_fault(vma, addr, pmd, flags,
+ ext4_get_block_dax, ext4_end_io_unwritten);
+
+ if (write) {
+ if (!IS_ERR(handle))
+ ext4_journal_stop(handle);
+ sb_end_pagefault(sb);
+ }
+
+ return result;
}
static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxxxx are
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