diff options
| author | Jan Kara <jack@suse.cz> | 2017-11-01 16:36:45 +0100 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2017-11-03 06:26:26 -0700 |
| commit | b8a6176c214cf9aa2679131ed7e4515cddaadc33 (patch) | |
| tree | e9b6ff2b1ee0459854e64f3195a7af7571b62196 /fs/ext4/file.c | |
| parent | 497f6926d880c57f65bf7c3f1086526fa774c55e (diff) | |
ext4: Support for synchronous DAX faults
We return IOMAP_F_DIRTY flag from ext4_iomap_begin() when asked to
prepare blocks for writing and the inode has some uncommitted metadata
changes. In the fault handler ext4_dax_fault() we then detect this case
(through VM_FAULT_NEEDDSYNC return value) and call helper
dax_finish_sync_fault() to flush metadata changes and insert page table
entry. Note that this will also dirty corresponding radix tree entry
which is what we want - fsync(2) will still provide data integrity
guarantees for applications not using userspace flushing. And
applications using userspace flushing can avoid calling fsync(2) and
thus avoid the performance overhead.
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'fs/ext4/file.c')
| -rw-r--r-- | fs/ext4/file.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 208adfc3e673..08a1d1a33a90 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -26,6 +26,7 @@ #include <linux/quotaops.h> #include <linux/pagevec.h> #include <linux/uio.h> +#include <linux/mman.h> #include "ext4.h" #include "ext4_jbd2.h" #include "xattr.h" @@ -295,6 +296,7 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf, */ bool write = (vmf->flags & FAULT_FLAG_WRITE) && (vmf->vma->vm_flags & VM_SHARED); + pfn_t pfn; if (write) { sb_start_pagefault(sb); @@ -310,9 +312,12 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf, } else { down_read(&EXT4_I(inode)->i_mmap_sem); } - result = dax_iomap_fault(vmf, pe_size, NULL, &ext4_iomap_ops); + result = dax_iomap_fault(vmf, pe_size, &pfn, &ext4_iomap_ops); if (write) { ext4_journal_stop(handle); + /* Handling synchronous page fault? */ + if (result & VM_FAULT_NEEDDSYNC) + result = dax_finish_sync_fault(vmf, pe_size, pfn); up_read(&EXT4_I(inode)->i_mmap_sem); sb_end_pagefault(sb); } else { @@ -350,6 +355,13 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) return -EIO; + /* + * We don't support synchronous mappings for non-DAX files. At least + * until someone comes with a sensible use case. + */ + if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC)) + return -EOPNOTSUPP; + file_accessed(file); if (IS_DAX(file_inode(file))) { vma->vm_ops = &ext4_dax_vm_ops; @@ -719,6 +731,7 @@ const struct file_operations ext4_file_operations = { .compat_ioctl = ext4_compat_ioctl, #endif .mmap = ext4_file_mmap, + .mmap_supported_flags = MAP_SYNC, .open = ext4_file_open, .release = ext4_release_file, .fsync = ext4_sync_file, |