xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

xfs: allocate delayed extents in CoW fork

Browse Source 
Modify the writepage handler to find and convert pending delalloc
extents to real allocations.  Furthermore, when we're doing non-cow
writes to a part of a file that already has a CoW reservation (the
cowextsz hint that we set up in a subsequent patch facilitates this),
promote the write to copy-on-write so that the entire extent can get
written out as a single extent on disk, thereby reducing post-CoW
fragmentation.

Christoph moved the CoW support code in _map_blocks to a separate helper
function, refactored other functions, and reduced the number of CoW fork
lookups, so I merged those changes here to reduce churn.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong
2016-10-03 09:11:34 -07:00
parent 60b4984fc3
commit ef4736678f
4 changed files with 170 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

97
fs/xfs/xfs_aops.c
View File

@@ -31,6 +31,7 @@
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_bmap_btree.h"
#include "xfs_reflink.h"
#include <linux/gfp.h>
#include <linux/mpage.h>
#include <linux/pagevec.h>
@@ -341,6 +342,7 @@ xfs_map_blocks(
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
ASSERT(type != XFS_IO_COW);
if (type == XFS_IO_UNWRITTEN)
bmapi_flags |= XFS_BMAPI_IGSTATE;
@@ -355,6 +357,13 @@ xfs_map_blocks(
offset_fsb = XFS_B_TO_FSBT(mp, offset);
error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
imap, &nimaps, bmapi_flags);
/*
* Truncate an overwrite extent if there's a pending CoW
* reservation before the end of this extent. This forces us
* to come back to writepage to take care of the CoW.
*/
if (nimaps && type == XFS_IO_OVERWRITE)
xfs_reflink_trim_irec_to_next_cow(ip, offset_fsb, imap);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error)
@@ -365,8 +374,7 @@ xfs_map_blocks(
error = xfs_iomap_write_allocate(ip, XFS_DATA_FORK, offset,
imap);
if (!error)
trace_xfs_map_blocks_alloc(ip, offset, count, type,
imap);
trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);
return error;
}
@@ -739,6 +747,56 @@ out_invalidate:
return;
}
static int
xfs_map_cow(
struct xfs_writepage_ctx *wpc,
struct inode *inode,
loff_t offset,
unsigned int *new_type)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_bmbt_irec imap;
bool is_cow = false, need_alloc = false;
int error;
/*
* If we already have a valid COW mapping keep using it.
*/
if (wpc->io_type == XFS_IO_COW) {
wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap, offset);
if (wpc->imap_valid) {
*new_type = XFS_IO_COW;
return 0;
}
}
/*
* Else we need to check if there is a COW mapping at this offset.
*/
xfs_ilock(ip, XFS_ILOCK_SHARED);
is_cow = xfs_reflink_find_cow_mapping(ip, offset, &imap, &need_alloc);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (!is_cow)
return 0;
/*
* And if the COW mapping has a delayed extent here we need to
* allocate real space for it now.
*/
if (need_alloc) {
error = xfs_iomap_write_allocate(ip, XFS_COW_FORK, offset,
&imap);
if (error)
return error;
}
wpc->io_type = *new_type = XFS_IO_COW;
wpc->imap_valid = true;
wpc->imap = imap;
return 0;
}
/*
* We implement an immediate ioend submission policy here to avoid needing to
* chain multiple ioends and hence nest mempool allocations which can violate
@@ -771,6 +829,7 @@ xfs_writepage_map(
int error = 0;
int count = 0;
int uptodate = 1;
unsigned int new_type;
bh = head = page_buffers(page);
offset = page_offset(page);
@@ -791,22 +850,13 @@ xfs_writepage_map(
continue;
}
if (buffer_unwritten(bh)) {
if (wpc->io_type != XFS_IO_UNWRITTEN) {
wpc->io_type = XFS_IO_UNWRITTEN;
wpc->imap_valid = false;
}
} else if (buffer_delay(bh)) {
if (wpc->io_type != XFS_IO_DELALLOC) {
wpc->io_type = XFS_IO_DELALLOC;
wpc->imap_valid = false;
}
} else if (buffer_uptodate(bh)) {
if (wpc->io_type != XFS_IO_OVERWRITE) {
wpc->io_type = XFS_IO_OVERWRITE;
wpc->imap_valid = false;
}
} else {
if (buffer_unwritten(bh))
new_type = XFS_IO_UNWRITTEN;
else if (buffer_delay(bh))
new_type = XFS_IO_DELALLOC;
else if (buffer_uptodate(bh))
new_type = XFS_IO_OVERWRITE;
else {
if (PageUptodate(page))
ASSERT(buffer_mapped(bh));
/*
@@ -819,6 +869,17 @@ xfs_writepage_map(
continue;
}
if (xfs_is_reflink_inode(XFS_I(inode))) {
error = xfs_map_cow(wpc, inode, offset, &new_type);
if (error)
goto out;
}
if (wpc->io_type != new_type) {
wpc->io_type = new_type;
wpc->imap_valid = false;
}
if (wpc->imap_valid)
wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap,
offset);