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ext4: convert DAX faults to iomap infrastructure 

Convert DAX faults to use iomap infrastructure. We would not have to start
transaction in ext4_dax_fault() anymore since ext4_iomap_begin takes
care of that but so far we do that to avoid lock inversion of
transaction start with DAX entry lock which gets acquired in
dax_iomap_fault() before calling ->iomap_begin handler.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara 2016-11-20 18:51:24 -05:00 committed by Theodore Ts'o
parent 96f8ba3dd6
commit e2ae766c1b
2 changed files with 14 additions and 9 deletions
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9
fs/ext4/file.c
View File

@ -275,7 +275,7 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
if (IS_ERR(handle))
result = VM_FAULT_SIGBUS;
else
result = dax_fault(vma, vmf, ext4_dax_get_block);
result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
if (write) {
if (!IS_ERR(handle))
@ -309,9 +309,10 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
if (IS_ERR(handle))
result = VM_FAULT_SIGBUS;
else
result = dax_pmd_fault(vma, addr, pmd, flags,
ext4_dax_get_block);
else {
result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
&ext4_iomap_ops);
}
if (write) {
if (!IS_ERR(handle))

14
fs/ext4/inode.c
View File

@ -3369,12 +3369,16 @@ retry:
}
/*
* If we added blocks beyond i_size we need to make sure they
* If we added blocks beyond i_size, we need to make sure they
* will get truncated if we crash before updating i_size in
* ext4_iomap_end().
* ext4_iomap_end(). For faults we don't need to do that (and
* even cannot because for orphan list operations inode_lock is
* required) - if we happen to instantiate block beyond i_size,
* it is because we race with truncate which has already added
* the inode to the orphan list.
*/
if (first_block + map.m_len >
(inode->i_size + (1 << blkbits) - 1) >> blkbits) {
if (!(flags & IOMAP_FAULT) && first_block + map.m_len >
(i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
int err;
err = ext4_orphan_add(handle, inode);
@ -3420,7 +3424,7 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
int blkbits = inode->i_blkbits;
bool truncate = false;
if (!(flags & IOMAP_WRITE))
if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
return 0;
handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);