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Subject[PATCH 5.0 108/238] ext4: cleanup pagecache before swap i_data
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: yangerkun <yangerkun@huawei.com>

commit a46c68a318b08f819047843abf349aeee5d10ac2 upstream.

While do swap, we should make sure there has no new dirty page since we
should swap i_data between two inode:
1.We should lock i_mmap_sem with write to avoid new pagecache from mmap
read/write;
2.Change filemap_flush to filemap_write_and_wait and move them to the
space protected by inode lock to avoid new pagecache from buffer read/write.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext4/ioctl.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -121,9 +121,6 @@ static long swap_inode_boot_loader(struc
return PTR_ERR(inode_bl);
ei_bl = EXT4_I(inode_bl);

- filemap_flush(inode->i_mapping);
- filemap_flush(inode_bl->i_mapping);
-
/* Protect orig inodes against a truncate and make sure,
* that only 1 swap_inode_boot_loader is running. */
lock_two_nondirectories(inode, inode_bl);
@@ -141,6 +138,15 @@ static long swap_inode_boot_loader(struc
goto journal_err_out;
}

+ down_write(&EXT4_I(inode)->i_mmap_sem);
+ err = filemap_write_and_wait(inode->i_mapping);
+ if (err)
+ goto err_out;
+
+ err = filemap_write_and_wait(inode_bl->i_mapping);
+ if (err)
+ goto err_out;
+
/* Wait for all existing dio workers */
inode_dio_wait(inode);
inode_dio_wait(inode_bl);
@@ -151,7 +157,7 @@ static long swap_inode_boot_loader(struc
handle = ext4_journal_start(inode_bl, EXT4_HT_MOVE_EXTENTS, 2);
if (IS_ERR(handle)) {
err = -EINVAL;
- goto journal_err_out;
+ goto err_out;
}

/* Protect extent tree against block allocations via delalloc */
@@ -208,6 +214,8 @@ static long swap_inode_boot_loader(struc
ext4_journal_stop(handle);
ext4_double_up_write_data_sem(inode, inode_bl);

+err_out:
+ up_write(&EXT4_I(inode)->i_mmap_sem);
journal_err_out:
unlock_two_nondirectories(inode, inode_bl);
iput(inode_bl);

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