pass-detailed-error-code-from-dax_iomap_fault

   1 dax: pass detailed error code from dax_iomap_fault()
   2
   3 From: Jan Kara <jack@suse.cz>
   4
   5 Ext4 needs to pass through error from its iomap handler to the page
   6 fault handler so that it can properly detect ENOSPC and force
   7 transaction commit and retry the fault (and block allocation). Add
   8 argument to dax_iomap_fault() for passing such error.
   9
  10 Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
  11 Signed-off-by: Jan Kara <jack@suse.cz>
  12 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  13 ---
  14  fs/dax.c            | 9 ++++++---
  15  fs/ext2/file.c      | 2 +-
  16  fs/ext4/file.c      | 2 +-
  17  fs/xfs/xfs_file.c   | 2 +-
  18  include/linux/dax.h | 2 +-
  19  5 files changed, 10 insertions(+), 7 deletions(-)
  20
  21 diff --git a/fs/dax.c b/fs/dax.c
  22 index 95981591977a..f3afa1d6156c 100644
  23 --- a/fs/dax.c
  24 +++ b/fs/dax.c
  25 @@ -1096,7 +1096,7 @@ static bool dax_fault_is_synchronous(unsigned long flags,
  26  }
  27
  28  static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
  29 -                              const struct iomap_ops *ops)
  30 +                              int *iomap_errp, const struct iomap_ops *ops)
  31  {
  32         struct vm_area_struct *vma = vmf->vma;
  33         struct address_space *mapping = vma->vm_file->f_mapping;
  34 @@ -1149,6 +1149,8 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
  35          * that we never have to deal with more than a single extent here.
  36          */
  37         error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
  38 +       if (iomap_errp)
  39 +               *iomap_errp = error;
  40         if (error) {
  41                 vmf_ret = dax_fault_return(error);
  42                 goto unlock_entry;
  43 @@ -1488,6 +1490,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
  44   * @vmf: The description of the fault
  45   * @pe_size: Size of the page to fault in
  46   * @pfnp: PFN to insert for synchronous faults if fsync is required
  47 + * @iomap_errp: Storage for detailed error code in case of error
  48   * @ops: Iomap ops passed from the file system
  49   *
  50   * When a page fault occurs, filesystems may call this helper in
  51 @@ -1496,11 +1499,11 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
  52   * successfully.
  53   */
  54  int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
  55 -                   pfn_t *pfnp, const struct iomap_ops *ops)
  56 +                   pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops)
  57  {
  58         switch (pe_size) {
  59         case PE_SIZE_PTE:
  60 -               return dax_iomap_pte_fault(vmf, pfnp, ops);
  61 +               return dax_iomap_pte_fault(vmf, pfnp, iomap_errp, ops);
  62         case PE_SIZE_PMD:
  63                 return dax_iomap_pmd_fault(vmf, pfnp, ops);
  64         default:
  65 diff --git a/fs/ext2/file.c b/fs/ext2/file.c
  66 index 2da67699dc33..09640220fda8 100644
  67 --- a/fs/ext2/file.c
  68 +++ b/fs/ext2/file.c
  69 @@ -100,7 +100,7 @@ static int ext2_dax_fault(struct vm_fault *vmf)
  70         }
  71         down_read(&ei->dax_sem);
  72
  73 -       ret = dax_iomap_fault(vmf, PE_SIZE_PTE, NULL, &ext2_iomap_ops);
  74 +       ret = dax_iomap_fault(vmf, PE_SIZE_PTE, NULL, NULL, &ext2_iomap_ops);
  75
  76         up_read(&ei->dax_sem);
  77         if (vmf->flags & FAULT_FLAG_WRITE)
  78 diff --git a/fs/ext4/file.c b/fs/ext4/file.c
  79 index a0ae27b1bc66..1c7cd882d998 100644
  80 --- a/fs/ext4/file.c
  81 +++ b/fs/ext4/file.c
  82 @@ -314,7 +314,7 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf,
  83         } else {
  84                 down_read(&EXT4_I(inode)->i_mmap_sem);
  85         }
  86 -       result = dax_iomap_fault(vmf, pe_size, &pfn, &ext4_iomap_ops);
  87 +       result = dax_iomap_fault(vmf, pe_size, &pfn, NULL, &ext4_iomap_ops);
  88         if (write) {
  89                 ext4_journal_stop(handle);
  90                 /* Handling synchronous page fault? */
  91 diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
  92 index 8601275cc5e6..9ea08326f876 100644
  93 --- a/fs/xfs/xfs_file.c
  94 +++ b/fs/xfs/xfs_file.c
  95 @@ -1048,7 +1048,7 @@ __xfs_filemap_fault(
  96         if (IS_DAX(inode)) {
  97                 pfn_t pfn;
  98
  99 -               ret = dax_iomap_fault(vmf, pe_size, &pfn, &xfs_iomap_ops);
 100 +               ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL, &xfs_iomap_ops);
 101                 if (ret & VM_FAULT_NEEDDSYNC)
 102                         ret = dax_finish_sync_fault(vmf, pe_size, pfn);
 103         } else {
 104 diff --git a/include/linux/dax.h b/include/linux/dax.h
 105 index 5258346c558c..0185ecdae135 100644
 106 --- a/include/linux/dax.h
 107 +++ b/include/linux/dax.h
 108 @@ -96,7 +96,7 @@ bool dax_write_cache_enabled(struct dax_device *dax_dev);
 109  ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
 110                 const struct iomap_ops *ops);
 111  int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
 112 -                   pfn_t *pfnp, const struct iomap_ops *ops);
 113 +                   pfn_t *pfnp, int *errp, const struct iomap_ops *ops);
 114  int dax_finish_sync_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
 115                           pfn_t pfn);
 116  int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
 117 --
 118 2.12.3
 119
 120