From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-btrfs@vger.kernel.org
Cc: kilobyte@angband.pl, linux-fsdevel@vger.kernel.org, jack@suse.cz,
david@fromorbit.com, willy@infradead.org, hch@lst.de,
darrick.wong@oracle.com, dsterba@suse.cz, nborisov@suse.com,
linux-nvdimm@lists.01.org, Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 04/18] dax: Introduce IOMAP_DAX_COW to CoW edges during writes
Date: Mon, 29 Apr 2019 12:26:35 -0500 [thread overview]
Message-ID: <20190429172649.8288-5-rgoldwyn@suse.de> (raw)
In-Reply-To: <20190429172649.8288-1-rgoldwyn@suse.de>
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
The IOMAP_DAX_COW is a iomap type which performs copy of
edges of data while performing a write if start/end are
not page aligned. The source address is expected in
iomap->inline_data.
dax_copy_edges() is a helper functions performs a copy from
one part of the device to another for data not page aligned.
If iomap->inline_data is NULL, it memset's the area to zero.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
fs/dax.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
include/linux/iomap.h | 1 +
2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/fs/dax.c b/fs/dax.c
index e5e54da1715f..610bfa861a28 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1084,6 +1084,42 @@ int __dax_zero_page_range(struct block_device *bdev,
}
EXPORT_SYMBOL_GPL(__dax_zero_page_range);
+/*
+ * dax_copy_edges - Copies the part of the pages not included in
+ * the write, but required for CoW because
+ * offset/offset+length are not page aligned.
+ */
+static int dax_copy_edges(struct inode *inode, loff_t pos, loff_t length,
+ struct iomap *iomap, void *daddr)
+{
+ unsigned offset = pos & (PAGE_SIZE - 1);
+ loff_t end = pos + length;
+ loff_t pg_end = round_up(end, PAGE_SIZE);
+ void *saddr = iomap->inline_data;
+ int ret = 0;
+ /*
+ * Copy the first part of the page
+ * Note: we pass offset as length
+ */
+ if (offset) {
+ if (saddr)
+ ret = memcpy_mcsafe(daddr, saddr, offset);
+ else
+ memset(daddr, 0, offset);
+ }
+
+ /* Copy the last part of the range */
+ if (end < pg_end) {
+ if (saddr)
+ ret = memcpy_mcsafe(daddr + offset + length,
+ saddr + offset + length, pg_end - end);
+ else
+ memset(daddr + offset + length, 0,
+ pg_end - end);
+ }
+ return ret;
+}
+
static loff_t
dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap)
@@ -1105,9 +1141,11 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
return iov_iter_zero(min(length, end - pos), iter);
}
- if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
+ if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED
+ && iomap->type != IOMAP_DAX_COW))
return -EIO;
+
/*
* Write can allocate block for an area which has a hole page mapped
* into page tables. We have to tear down these mappings so that data
@@ -1144,6 +1182,12 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
break;
}
+ if (iomap->type == IOMAP_DAX_COW) {
+ ret = dax_copy_edges(inode, pos, length, iomap, kaddr);
+ if (ret)
+ break;
+ }
+
map_len = PFN_PHYS(map_len);
kaddr += offset;
map_len -= offset;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 0fefb5455bda..6e885c5a38a3 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -25,6 +25,7 @@ struct vm_fault;
#define IOMAP_MAPPED 0x03 /* blocks allocated at @addr */
#define IOMAP_UNWRITTEN 0x04 /* blocks allocated at @addr in unwritten state */
#define IOMAP_INLINE 0x05 /* data inline in the inode */
+#define IOMAP_DAX_COW 0x06 /* Copy data pointed by inline_data before write*/
/*
* Flags for all iomap mappings:
--
2.16.4
next prev parent reply other threads:[~2019-04-29 17:27 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-29 17:26 [PATCH v4 00/18] btrfs dax support Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 01/18] btrfs: create a mount option for dax Goldwyn Rodrigues
2019-05-21 18:02 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 02/18] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 03/18] btrfs: basic dax read Goldwyn Rodrigues
2019-05-21 15:14 ` Darrick J. Wong
2019-05-22 21:50 ` Goldwyn Rodrigues
2019-04-29 17:26 ` Goldwyn Rodrigues [this message]
2019-05-21 16:51 ` [PATCH 04/18] dax: Introduce IOMAP_DAX_COW to CoW edges during writes Darrick J. Wong
2019-05-22 20:14 ` Goldwyn Rodrigues
2019-05-23 2:10 ` Dave Chinner
2019-05-23 9:05 ` Shiyang Ruan
2019-05-23 11:51 ` Goldwyn Rodrigues
2019-05-27 8:25 ` Shiyang Ruan
2019-05-28 9:17 ` Jan Kara
2019-05-29 2:01 ` Shiyang Ruan
2019-05-29 2:47 ` Dave Chinner
2019-05-29 4:02 ` Shiyang Ruan
2019-05-29 4:07 ` Darrick J. Wong
2019-05-29 4:46 ` Dave Chinner
2019-05-29 13:46 ` Jan Kara
2019-05-29 22:14 ` Dave Chinner
2019-05-30 11:16 ` Jan Kara
2019-05-30 22:59 ` Dave Chinner
2019-04-29 17:26 ` [PATCH 05/18] btrfs: return whether extent is nocow or not Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 06/18] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 07/18] btrfs: add dax write support Goldwyn Rodrigues
2019-05-21 17:08 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 08/18] dax: memcpy page in case of IOMAP_DAX_COW for mmap faults Goldwyn Rodrigues
2019-05-21 17:46 ` Darrick J. Wong
2019-05-22 19:11 ` Goldwyn Rodrigues
2019-05-23 4:02 ` Darrick J. Wong
2019-05-23 12:10 ` Jan Kara
2019-04-29 17:26 ` [PATCH 09/18] btrfs: Add dax specific address_space_operations Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 10/18] dax: replace mmap entry in case of CoW Goldwyn Rodrigues
2019-05-21 17:35 ` Darrick J. Wong
2019-05-23 13:38 ` Jan Kara
2019-04-29 17:26 ` [PATCH 11/18] btrfs: add dax mmap support Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 12/18] btrfs: allow MAP_SYNC mmap Goldwyn Rodrigues
2019-05-10 15:32 ` [PATCH for-goldwyn] btrfs: disallow MAP_SYNC outside of DAX mounts Adam Borowski
2019-05-10 15:41 ` Dan Williams
2019-05-10 15:59 ` Pankaj Gupta
2019-05-23 13:44 ` [PATCH 12/18] btrfs: allow MAP_SYNC mmap Jan Kara
2019-05-23 16:19 ` Adam Borowski
2019-04-29 17:26 ` [PATCH 13/18] fs: dedup file range to use a compare function Goldwyn Rodrigues
2019-05-21 18:17 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 14/18] dax: memcpy before zeroing range Goldwyn Rodrigues
2019-05-21 17:27 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 15/18] btrfs: handle dax page zeroing Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 16/18] btrfs: Writeprotect mmap pages on snapshot Goldwyn Rodrigues
2019-05-23 14:04 ` Jan Kara
2019-05-23 15:27 ` Goldwyn Rodrigues
2019-05-23 19:07 ` Jan Kara
2019-05-23 21:22 ` Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 17/18] btrfs: Disable dax-based defrag and send Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 18/18] btrfs: trace functions for btrfs_iomap_begin/end Goldwyn Rodrigues
-- strict thread matches above, loose matches on Subject: below --
2019-04-16 16:41 [PATCH v3 00/18] btrfs dax support Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 04/18] dax: Introduce IOMAP_DAX_COW to CoW edges during writes Goldwyn Rodrigues
2019-04-17 16:46 ` Darrick J. Wong
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