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authorMikulas Patocka <mpatocka@redhat.com>2020-09-05 08:13:02 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-09-09 19:04:28 +0200
commit884fee7632168ab59ed49a26de430fa3ed5c6a86 (patch)
tree36355a90b286c56f3e59b110d11af867ec07e5f5
parentda0d5ccf845fd5337ce9afaddd46e99859f78502 (diff)
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xfs: don't update mtime on COW faults
commit b17164e258e3888d376a7434415013175d637377 upstream. When running in a dax mode, if the user maps a page with MAP_PRIVATE and PROT_WRITE, the xfs filesystem would incorrectly update ctime and mtime when the user hits a COW fault. This breaks building of the Linux kernel. How to reproduce: 1. extract the Linux kernel tree on dax-mounted xfs filesystem 2. run make clean 3. run make -j12 4. run make -j12 at step 4, make would incorrectly rebuild the whole kernel (although it was already built in step 3). The reason for the breakage is that almost all object files depend on objtool. When we run objtool, it takes COW page fault on its .data section, and these faults will incorrectly update the timestamp of the objtool binary. The updated timestamp causes make to rebuild the whole tree. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/xfs/xfs_file.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 259549698ba7..f22acfd53850 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1095,6 +1095,14 @@ __xfs_filemap_fault(
return ret;
}
+static inline bool
+xfs_is_write_fault(
+ struct vm_fault *vmf)
+{
+ return (vmf->flags & FAULT_FLAG_WRITE) &&
+ (vmf->vma->vm_flags & VM_SHARED);
+}
+
static vm_fault_t
xfs_filemap_fault(
struct vm_fault *vmf)
@@ -1102,7 +1110,7 @@ xfs_filemap_fault(
/* DAX can shortcut the normal fault path on write faults! */
return __xfs_filemap_fault(vmf, PE_SIZE_PTE,
IS_DAX(file_inode(vmf->vma->vm_file)) &&
- (vmf->flags & FAULT_FLAG_WRITE));
+ xfs_is_write_fault(vmf));
}
static vm_fault_t
@@ -1115,7 +1123,7 @@ xfs_filemap_huge_fault(
/* DAX can shortcut the normal fault path on write faults! */
return __xfs_filemap_fault(vmf, pe_size,
- (vmf->flags & FAULT_FLAG_WRITE));
+ xfs_is_write_fault(vmf));
}
static vm_fault_t