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jfs: makes diUnmount/diMount in jfs_mount_rw atomic

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jfs_mount_rw can call diUnmount and then diMount. These calls change the
imap pointer. Between these two calls there may be calls of function
jfs_lookup(). The jfs_lookup() function calls jfs_iget(), which, in turn
calls diRead(). The latter references the imap pointer. That may cause
diRead() to refer to a pointer freed in diUnmount().  This commit makes
the calls to diUnmount()/diMount() atomic so that nothing will read the
imap pointer until the whole remount is completed.

Signed-off-by: Oleg Kanatov <okanatov@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
This commit is contained in:
Oleg Kanatov 2022-10-28 15:22:54 +03:00 committed by Dave Kleikamp
parent d0e482c45c
commit a60dca73a1
2 changed files with 5 additions and 1 deletions
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2
fs/jfs/jfs_imap.c
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@ -310,8 +310,8 @@ int diRead(struct inode *ip)
iagno = INOTOIAG(ip->i_ino);
/* read the iag */
imap = JFS_IP(ipimap)->i_imap;
IREAD_LOCK(ipimap, RDWRLOCK_IMAP);
imap = JFS_IP(ipimap)->i_imap;
rc = diIAGRead(imap, iagno, &mp);
IREAD_UNLOCK(ipimap);
if (rc) {

4
fs/jfs/jfs_mount.c
View File

@ -234,11 +234,15 @@ int jfs_mount_rw(struct super_block *sb, int remount)
truncate_inode_pages(sbi->ipimap->i_mapping, 0);
truncate_inode_pages(sbi->ipbmap->i_mapping, 0);
IWRITE_LOCK(sbi->ipimap, RDWRLOCK_IMAP);
diUnmount(sbi->ipimap, 1);
if ((rc = diMount(sbi->ipimap))) {
IWRITE_UNLOCK(sbi->ipimap);
jfs_err("jfs_mount_rw: diMount failed!");
return rc;
}
IWRITE_UNLOCK(sbi->ipimap);
dbUnmount(sbi->ipbmap, 1);
if ((rc = dbMount(sbi->ipbmap))) {