[PATCH] fs: Convert open-coded "is inode open for write" check

* [PATCH] fs: Convert open-coded "is inode open for write" check
@ 2018-12-10 13:19 Nikolay Borisov
  2018-12-10 13:25 ` [PATCH v2] " Nikolay Borisov
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Nikolay Borisov @ 2018-12-10 13:19 UTC (permalink / raw)
  To: linux-fsdevel
  Cc: jack, linux-integrity, zohar, amir73il, jmorris, jlayton, tytso,
	linux-ext4, akpm, adilger.kernel, Nikolay Borisov

There is a generic helper inode_is_open_for_write that could be used
when checking i_writecount. Use it instead of opencoding
if (i_writecount > 0) check. Also the checks in ext4 seem to be wrong since 
they will also evaluate to true when i_writecount is MMAP_DENY_WRITE (< 0)

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---

Andrew, 

Please take this patch after the ext4 people have sent their RB/Acks. 
Alternatively I can split the ext4 changes in a separate patch and send you just
the rest. 

 fs/ext4/inode.c                    | 2 +-
 fs/ext4/mballoc.c                  | 7 +++----
 fs/locks.c                         | 2 +-
 fs/notify/fanotify/fanotify_user.c | 2 +-
 security/integrity/ima/ima_main.c  | 2 +-
 5 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 22a9d8159720..04e5bc0b5c8d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -391,7 +391,7 @@ void ext4_da_update_reserve_space(struct inode *inode,
 	 * inode's preallocations.
 	 */
 	if ((ei->i_reserved_data_blocks == 0) &&
-	    (atomic_read(&inode->i_writecount) == 0))
+	    !inode_is_open_for_write(inode))
 		ext4_discard_preallocations(inode);
 }
 
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e2248083cdca..7b656ec9a333 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4176,9 +4176,8 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
 	isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)
 		>> bsbits;
 
-	if ((size == isize) &&
-	    !ext4_fs_is_busy(sbi) &&
-	    (atomic_read(&ac->ac_inode->i_writecount) == 0)) {
+	if ((size == isize) && !ext4_fs_is_busy(sbi)
+	    && !inode_is_open_for_write(inode) {
 		ac->ac_flags |= EXT4_MB_HINT_NOPREALLOC;
 		return;
 	}
@@ -4258,7 +4257,7 @@ ext4_mb_initialize_context(struct ext4_allocation_context *ac,
 			(unsigned) ar->goal, ac->ac_flags, ac->ac_2order,
 			(unsigned) ar->lleft, (unsigned) ar->pleft,
 			(unsigned) ar->lright, (unsigned) ar->pright,
-			atomic_read(&ar->inode->i_writecount) ? "" : "non-");
+			inode_is_open_for_write(&ar->inode) ? "" : "non-");
 	return 0;
 
 }
diff --git a/fs/locks.c b/fs/locks.c
index 2ecb4db8c840..f71142269dd3 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1646,7 +1646,7 @@ check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
 	if (flags & FL_LAYOUT)
 		return 0;
 
-	if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
+	if ((arg == F_RDLCK) && inode_is_open_for_write(&inode))
 		return -EAGAIN;
 
 	if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index e03be5071362..98b0769e4cf2 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -669,7 +669,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
 	 */
 	if ((flags & FAN_MARK_IGNORED_MASK) &&
 	    !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
-	    (atomic_read(&inode->i_writecount) > 0))
+	    inode_is_open_for_write(inode))
 		return 0;
 
 	return fanotify_add_mark(group, &inode->i_fsnotify_marks,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 1b88d58e1325..05fbf8a2fa42 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -103,7 +103,7 @@ static void ima_rdwr_violation_check(struct file *file,
 	} else {
 		if (must_measure)
 			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
-		if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
+		if (inode_is_open_for_write(inode) && must_measure)
 			send_writers = true;
 	}
 
-- 
2.17.1


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