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ext4: Convert to use mapping->invalidate_lock

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Convert ext4 to use mapping->invalidate_lock instead of its private
EXT4_I(inode)->i_mmap_sem. This is mostly search-and-replace. By this
conversion we fix a long standing race between hole punching and read(2)
/ readahead(2) paths that can lead to stale page cache contents.

CC: <linux-ext4@vger.kernel.org>
CC: Ted Tso <tytso@mit.edu>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara
2021-02-04 18:05:42 +01:00
parent 7506ae6a70
commit d4f5258eae
7 changed files with 50 additions and 70 deletions
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13
fs/ext4/file.c
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@@ -704,22 +704,23 @@ static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
*/
bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
(vmf->vma->vm_flags & VM_SHARED);
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
pfn_t pfn;
if (write) {
sb_start_pagefault(sb);
file_update_time(vmf->vma->vm_file);
down_read(&EXT4_I(inode)->i_mmap_sem);
filemap_invalidate_lock_shared(mapping);
retry:
handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
EXT4_DATA_TRANS_BLOCKS(sb));
if (IS_ERR(handle)) {
up_read(&EXT4_I(inode)->i_mmap_sem);
filemap_invalidate_unlock_shared(mapping);
sb_end_pagefault(sb);
return VM_FAULT_SIGBUS;
}
} else {
down_read(&EXT4_I(inode)->i_mmap_sem);
filemap_invalidate_lock_shared(mapping);
}
result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
if (write) {
@@ -731,10 +732,10 @@ retry:
/* 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);
filemap_invalidate_unlock_shared(mapping);
sb_end_pagefault(sb);
} else {
up_read(&EXT4_I(inode)->i_mmap_sem);
filemap_invalidate_unlock_shared(mapping);
}
return result;
@@ -756,7 +757,7 @@ static const struct vm_operations_struct ext4_dax_vm_ops = {
#endif
static const struct vm_operations_struct ext4_file_vm_ops = {
.fault = ext4_filemap_fault,
.fault = filemap_fault,
.map_pages = filemap_map_pages,
.page_mkwrite = ext4_page_mkwrite,
};