From e411d74cc5ba290f85d0dd5e4d1df8f1d6d975d2 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Thu, 5 Feb 2026 15:52:57 +0100 Subject: [PATCH] gfs2: fiemap page fault fix In gfs2_fiemap(), we are calling iomap_fiemap() while holding the inode glock. This can lead to recursive glock taking if the fiemap buffer is memory mapped to the same inode and accessing it triggers a page fault. Fix by disabling page faults for iomap_fiemap() and faulting in the buffer by hand if necessary. Fixes xfstest generic/742. Signed-off-by: Andreas Gruenbacher --- fs/gfs2/inode.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index b6ed069b34872..4d65e4a752626 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -2192,6 +2192,14 @@ static int gfs2_getattr(struct mnt_idmap *idmap, return 0; } +static bool fault_in_fiemap(struct fiemap_extent_info *fi) +{ + struct fiemap_extent __user *dest = fi->fi_extents_start; + size_t size = sizeof(*dest) * fi->fi_extents_max; + + return fault_in_safe_writeable((char __user *)dest, size) == 0; +} + static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, u64 start, u64 len) { @@ -2201,14 +2209,22 @@ static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, inode_lock_shared(inode); +retry: ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh); if (ret) goto out; + pagefault_disable(); ret = iomap_fiemap(inode, fieinfo, start, len, &gfs2_iomap_ops); + pagefault_enable(); gfs2_glock_dq_uninit(&gh); + if (ret == -EFAULT && fault_in_fiemap(fieinfo)) { + fieinfo->fi_extents_mapped = 0; + goto retry; + } + out: inode_unlock_shared(inode); return ret; -- 2.47.3