From: Qu Wenruo <wqu@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: Filipe Manana <fdmanana@suse.com>
Subject: [PATCH v5 3/3] btrfs: add extra sanity checks for create_io_em()
Date: Tue, 16 Apr 2024 09:05:40 +0930 [thread overview]
Message-ID: <b63666662f99e0c93b192bfb539e4d697436c4f4.1713224013.git.wqu@suse.com> (raw)
In-Reply-To: <cover.1713224013.git.wqu@suse.com>
The function create_io_em() is called before we submit an IO, to update
the in-memory extent map for the involved range.
This patch changes the following aspects:
- Does not allow BTRFS_ORDERED_NOCOW type
For real NOCOW (excluding NOCOW writes into preallocated ranges)
writes, we never call create_io_em(), as we does not need to update
the extent map at all.
So remove the sanity check allowing BTRFS_ORDERED_NOCOW type.
- Add extra sanity checks
* PREALLOC
- @block_len == len
For uncompressed writes.
* REGULAR
- @block_len == @orig_block_len == @ram_bytes == @len
We're creating a new uncompressed extent, and referring all of it.
- @orig_start == @start
We haven no offset inside the extent.
* COMPRESSED
- valid @compress_type
- @len <= @ram_bytes
This is to co-operate with encoded writes, which can cause a new
file extent referring only part of a uncompressed extent.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/inode.c | 40 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c6f2b5d1dee1..ced916f42bab 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7320,11 +7320,49 @@ static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
struct extent_map *em;
int ret;
+ /*
+ * Note the missing of NOCOW type.
+ *
+ * For pure NOCOW writes, we should not create an io extent map,
+ * but just reusing the existing one.
+ * Only PREALLOC writes (NOCOW write into preallocated range) can
+ * create io extent map.
+ */
ASSERT(type == BTRFS_ORDERED_PREALLOC ||
type == BTRFS_ORDERED_COMPRESSED ||
- type == BTRFS_ORDERED_NOCOW ||
type == BTRFS_ORDERED_REGULAR);
+ switch (type) {
+ case BTRFS_ORDERED_PREALLOC:
+ /* Uncompressed extents. */
+ ASSERT(block_len == len);
+
+ /* We're only referring part of a larger preallocated extent. */
+ ASSERT(block_len <= ram_bytes);
+ break;
+ case BTRFS_ORDERED_REGULAR:
+ /* Uncompressed extents. */
+ ASSERT(block_len == len);
+
+ /* COW results a new extent matching our file extent size. */
+ ASSERT(orig_block_len == len);
+ ASSERT(ram_bytes == len);
+
+ /* Since it's a new extent, we should not have any offset. */
+ ASSERT(orig_start == start);
+ break;
+ case BTRFS_ORDERED_COMPRESSED:
+ /* Must be compressed. */
+ ASSERT(compress_type != BTRFS_COMPRESS_NONE);
+
+ /*
+ * Encoded write can make us to refer to part of the
+ * uncompressed extent.
+ */
+ ASSERT(len <= ram_bytes);
+ break;
+ }
+
em = alloc_extent_map();
if (!em)
return ERR_PTR(-ENOMEM);
--
2.44.0
prev parent reply other threads:[~2024-04-15 23:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-15 23:35 [PATCH v5 0/3] btrfs: more explaination on extent_map members Qu Wenruo
2024-04-15 23:35 ` [PATCH v5 1/3] btrfs: add extra comments " Qu Wenruo
2024-04-15 23:35 ` [PATCH v5 2/3] btrfs: simplify the inline extent map creation Qu Wenruo
2024-04-15 23:35 ` Qu Wenruo [this message]
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