[PATCH 5.15 07/20] btrfs: zoned: only allow one process to add pages to a relocation inode

Greg Kroah-Hartman
2021-11-19T17:42:10Z

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

commit 35156d852762b58855f513b4f8bb7f32d69dc9c5 upstream

Don't allow more than one process to add pages to a relocation inode on
a zoned filesystem, otherwise we cannot guarantee the sequential write
rule once we're filling preallocated extents on a zoned filesystem.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/extent_io.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5120,6 +5120,9 @@ int extent_write_locked_range(struct ino
int extent_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
+ struct inode *inode = mapping->host;
+ const bool data_reloc = btrfs_is_data_reloc_root(BTRFS_I(inode)->root);
+ const bool zoned = btrfs_is_zoned(BTRFS_I(inode)->root->fs_info);
int ret = 0;
struct extent_page_data epd = {
.bio_ctrl = { 0 },
@@ -5127,7 +5130,15 @@ int extent_writepages(struct address_spa
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
};

+ /*
+ * Allow only a single thread to do the reloc work in zoned mode to
+ * protect the write pointer updates.
+ */
+ if (data_reloc && zoned)
+ btrfs_inode_lock(inode, 0);
ret = extent_write_cache_pages(mapping, wbc, &epd);
+ if (data_reloc && zoned)
+ btrfs_inode_unlock(inode, 0);
ASSERT(ret <= 0);
if (ret < 0) {
end_write_bio(&epd, ret);