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xfs: cleanup xfs_direct_write_iomap_begin

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Move more checks into the helpers that determine if we need a COW
operation or allocation and split the return path for when an existing
data for allocation has been found versus a new allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Christoph Hellwig 2019-10-19 09:09:47 -07:00 committed by Darrick J. Wong
parent 12dfb58af6
commit 5c5b6f7585
1 changed files with 46 additions and 42 deletions
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88
fs/xfs/xfs_iomap.c
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@ -642,23 +642,42 @@ error_on_bmapi_transaction:
static inline bool
imap_needs_alloc(
struct inode *inode,
unsigned flags,
struct xfs_bmbt_irec *imap,
int nimaps)
{
return !nimaps ||
imap->br_startblock == HOLESTARTBLOCK ||
imap->br_startblock == DELAYSTARTBLOCK ||
(IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);
/* don't allocate blocks when just zeroing */
if (flags & IOMAP_ZERO)
return false;
if (!nimaps ||
imap->br_startblock == HOLESTARTBLOCK ||
imap->br_startblock == DELAYSTARTBLOCK)
return true;
/* we convert unwritten extents before copying the data for DAX */
if (IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN)
return true;
return false;
}
static inline bool
needs_cow_for_zeroing(
imap_needs_cow(
struct xfs_inode *ip,
unsigned int flags,
struct xfs_bmbt_irec *imap,
int nimaps)
{
return nimaps &&
imap->br_startblock != HOLESTARTBLOCK &&
imap->br_state != XFS_EXT_UNWRITTEN;
if (!xfs_is_cow_inode(ip))
return false;
/* when zeroing we don't have to COW holes or unwritten extents */
if (flags & IOMAP_ZERO) {
if (!nimaps ||
imap->br_startblock == HOLESTARTBLOCK ||
imap->br_state == XFS_EXT_UNWRITTEN)
return false;
}
return true;
}
static int
@ -742,6 +761,14 @@ xfs_direct_write_iomap_begin(
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
/*
* Writes that span EOF might trigger an IO size update on completion,
* so consider them to be dirty for the purposes of O_DSYNC even if
* there is no other metadata changes pending or have been made here.
*/
if (offset + length > i_size_read(inode))
iomap_flags |= IOMAP_F_DIRTY;
/*
* Lock the inode in the manner required for the specified operation and
* check for as many conditions that would result in blocking as
@ -761,12 +788,7 @@ xfs_direct_write_iomap_begin(
* Break shared extents if necessary. Checks for non-blocking IO have
* been done up front, so we don't need to do them here.
*/
if (xfs_is_cow_inode(ip)) {
/* if zeroing doesn't need COW allocation, then we are done. */
if ((flags & IOMAP_ZERO) &&
!needs_cow_for_zeroing(&imap, nimaps))
goto out_found;
if (imap_needs_cow(ip, flags, &imap, nimaps)) {
/* may drop and re-acquire the ilock */
error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
&lockmode, flags & IOMAP_DIRECT);
@ -778,18 +800,17 @@ xfs_direct_write_iomap_begin(
length = XFS_FSB_TO_B(mp, end_fsb) - offset;
}
/* Don't need to allocate over holes when doing zeroing operations. */
if (flags & IOMAP_ZERO)
goto out_found;
if (imap_needs_alloc(inode, flags, &imap, nimaps))
goto allocate_blocks;
if (!imap_needs_alloc(inode, &imap, nimaps))
goto out_found;
xfs_iunlock(ip, lockmode);
trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags);
/* If nowait is set bail since we are going to make allocations. */
if (flags & IOMAP_NOWAIT) {
error = -EAGAIN;
allocate_blocks:
error = -EAGAIN;
if (flags & IOMAP_NOWAIT)
goto out_unlock;
}
/*
* We cap the maximum length we map to a sane size to keep the chunks
@ -808,29 +829,12 @@ xfs_direct_write_iomap_begin(
*/
if (lockmode == XFS_ILOCK_EXCL)
xfs_ilock_demote(ip, lockmode);
error = xfs_iomap_write_direct(ip, offset, length, &imap,
nimaps);
error = xfs_iomap_write_direct(ip, offset, length, &imap, nimaps);
if (error)
return error;
iomap_flags |= IOMAP_F_NEW;
trace_xfs_iomap_alloc(ip, offset, length, XFS_DATA_FORK, &imap);
out_finish:
/*
* Writes that span EOF might trigger an IO size update on completion,
* so consider them to be dirty for the purposes of O_DSYNC even if
* there is no other metadata changes pending or have been made here.
*/
if (offset + length > i_size_read(inode))
iomap_flags |= IOMAP_F_DIRTY;
return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags);
out_found:
ASSERT(nimaps);
xfs_iunlock(ip, lockmode);
trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
goto out_finish;
return xfs_bmbt_to_iomap(ip, iomap, &imap, iomap_flags | IOMAP_F_NEW);
out_found_cow:
xfs_iunlock(ip, lockmode);