[Devel] [PATCH RHEL8 COMMIT] ms/fs/direct-io.c: keep dio_warn_stale_pagecache() when CONFIG_BLOCK=n

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.47
------>
commit 22736ab4064a279c3a47d32c3d25f9625413e40a
Author: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
Date:   Mon Jun 21 20:56:50 2021 +0300

    ms/fs/direct-io.c: keep dio_warn_stale_pagecache() when CONFIG_BLOCK=n
    
    This helper prints warning if direct I/O write failed to invalidate cache,
    and set EIO at inode to warn usersapce about possible data corruption.
    
    See also commit 5a9d929d6e13 ("iomap: report collisions between directio
    and buffered writes to userspace").
    
    Direct I/O is supported by non-disk filesystems, for example NFS.  Thus
    generic code needs this even in kernel without CONFIG_BLOCK.
    
    Link: http://lkml.kernel.org/r/157270038074.4812.7980855544557488880.stgit@buzz
    Signed-off-by: Konstantin Khlebnikov <khlebnikov at yandex-team.ru>
    
    Reviewed-by: Andrew Morton <akpm at linux-foundation.org>
    Reviewed-by: Jan Kara <jack at suse.cz>
    Cc: Jens Axboe <axboe at kernel.dk>
    Cc: Alexander Viro <viro at zeniv.linux.org.uk>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    (cherry-picked from ms commit a92853b6746fe5ffef20a7c30addf6320561e669)
    https://jira.sw.ru/browse/PSBM-124609
    
    (cherry-picked from vz7 commit 856aa6dcb2c178882352752baf4805952207eff0)
    
    https://jira.sw.ru/browse/PSBM-127858
    Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
---
 fs/direct-io.c     | 21 ---------------------
 include/linux/fs.h |  6 +++++-
 mm/filemap.c       | 21 +++++++++++++++++++++
 3 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index dbc1a1f080ce..e19ce7e11acd 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -219,27 +219,6 @@ static inline struct page *dio_get_page(struct dio *dio,
 	return dio->pages[sdio->head];
 }
 
-/*
- * Warn about a page cache invalidation failure during a direct io write.
- */
-void dio_warn_stale_pagecache(struct file *filp)
-{
-	static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
-	char pathname[128];
-	struct inode *inode = file_inode(filp);
-	char *path;
-
-	errseq_set(&inode->i_mapping->wb_err, -EIO);
-	if (__ratelimit(&_rs)) {
-		path = file_path(filp, pathname, sizeof(pathname));
-		if (IS_ERR(path))
-			path = "(unknown)";
-		pr_crit("Page cache invalidation failure on direct I/O.  Possible data corruption due to collision with buffered I/O!\n");
-		pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
-			current->comm);
-	}
-}
-
 /**
  * dio_complete() - called when all DIO BIO I/O has been completed
  * @offset: the byte offset in the file of the completed operation
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0a54b95dc1b4..512cc99c39af 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3168,7 +3168,6 @@ enum {
 };
 
 void dio_end_io(struct bio *bio);
-void dio_warn_stale_pagecache(struct file *filp);
 
 ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 			     struct block_device *bdev, struct iov_iter *iter,
@@ -3213,6 +3212,11 @@ static inline void inode_dio_end(struct inode *inode)
 		wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
 }
 
+/*
+ * Warn about a page cache invalidation failure diring a direct I/O write.
+ */
+void dio_warn_stale_pagecache(struct file *filp);
+
 extern void inode_set_flags(struct inode *inode, unsigned int flags,
 			    unsigned int mask);
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 2703749cd35a..2c79922324ba 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3148,6 +3148,27 @@ int pagecache_write_end(struct file *file, struct address_space *mapping,
 }
 EXPORT_SYMBOL(pagecache_write_end);
 
+/*
+ * Warn about a page cache invalidation failure during a direct io write.
+ */
+void dio_warn_stale_pagecache(struct file *filp)
+{
+	static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
+	char pathname[128];
+	struct inode *inode = file_inode(filp);
+	char *path;
+
+	errseq_set(&inode->i_mapping->wb_err, -EIO);
+	if (__ratelimit(&_rs)) {
+		path = file_path(filp, pathname, sizeof(pathname));
+		if (IS_ERR(path))
+			path = "(unknown)";
+		pr_crit("Page cache invalidation failure on direct I/O.  Possible data corruption due to collision with buffered I/O!\n");
+		pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
+			current->comm);
+	}
+}
+
 ssize_t
 generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
 {