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I cleaned up the commit message a little and removed a couple blank lines. Thanks! On 10/28/22 7:22AM, Oleg Kanatov wrote: > jfs_mount_rw can call diUnmount and then diMount. These calls > change the imap pointer. > In case JFS filesystem is mounted on root (/), between these two > calls there may be calls of function jfs_lookup(). > The jfs_lookup() function calls jfs_iget(), which, in its turn, > calls diRead(). The latter references the imap pointer. > That may cause diRead() to refer to a pointer "freed" in > diUnmount(). > This commit makes calls diUnmount()/diMount() be atomic so that > nothing will read the imap pointer until the whole remount is > completed. > > Signed-off-by: Oleg Kanatov > --- > fs/jfs/jfs_imap.c | 2 +- > fs/jfs/jfs_mount.c | 6 ++++++ > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c > index 799d3837e7c2..390cbfce391f 100644 > --- a/fs/jfs/jfs_imap.c > +++ b/fs/jfs/jfs_imap.c > @@ -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) { > diff --git a/fs/jfs/jfs_mount.c b/fs/jfs/jfs_mount.c > index 48d1f70f786c..972b9ff18723 100644 > --- a/fs/jfs/jfs_mount.c > +++ b/fs/jfs/jfs_mount.c > @@ -234,12 +234,18 @@ 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))) { > jfs_err("jfs_mount_rw: dbMount failed!");