6.18-stable review patch. If anyone has any objections, please let me know.
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From: Yuezhang Mo Yuezhang.Mo@sony.com
[ Upstream commit 4e163c39dd4e70fcdce948b8774d96e0482b4a11 ]
xfstests generic/363 was failing due to unzeroed post-EOF page cache that allowed mmap writes beyond EOF to become visible after file extension.
For example, in following xfs_io sequence, 0x22 should not be written to the file but would become visible after the extension:
xfs_io -f -t -c "pwrite -S 0x11 0 8" \ -c "mmap 0 4096" \ -c "mwrite -S 0x22 32 32" \ -c "munmap" \ -c "pwrite -S 0x33 512 32" \ $testfile
This violates the expected behavior where writes beyond EOF via mmap should not persist after the file is extended. Instead, the extended region should contain zeros.
Fix this by using truncate_pagecache() to truncate the page cache after the current EOF when extending the file.
Signed-off-by: Yuezhang Mo Yuezhang.Mo@sony.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/exfat/file.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/fs/exfat/file.c b/fs/exfat/file.c index adc37b4d7fc2..536c8078f0c1 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -25,6 +25,8 @@ static int exfat_cont_expand(struct inode *inode, loff_t size) struct exfat_sb_info *sbi = EXFAT_SB(sb); struct exfat_chain clu;
+ truncate_pagecache(inode, i_size_read(inode)); + ret = inode_newsize_ok(inode, size); if (ret) return ret; @@ -639,6 +641,9 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
inode_lock(inode);
+ if (pos > i_size_read(inode)) + truncate_pagecache(inode, i_size_read(inode)); + valid_size = ei->valid_size;
ret = generic_write_checks(iocb, iter);