[PATCH 05/14] ext4: Convert to use mapping->invalidate_lock

Jan Kara
2021-06-07T14:52:47Z

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>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/ext4/ext4.h | 10 ----------
fs/ext4/extents.c | 25 +++++++++++++-----------
fs/ext4/file.c | 13 +++++++------
fs/ext4/inode.c | 47 +++++++++++++++++-----------------------------
fs/ext4/ioctl.c | 4 ++--
fs/ext4/super.c | 13 +++++--------
fs/ext4/truncate.h | 8 +++++---
7 files changed, 50 insertions(+), 70 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 37002663d521..ed64b4b217a1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1077,15 +1077,6 @@ struct ext4_inode_info {
* by other means, so we have i_data_sem.
*/
struct rw_semaphore i_data_sem;
- /*
- * i_mmap_sem is for serializing page faults with truncate / punch hole
- * operations. We have to make sure that new page cannot be faulted in
- * a section of the inode that is being punched. We cannot easily use
- * i_data_sem for this since we need protection for the whole punch
- * operation and i_data_sem ranks below transaction start so we have
- * to occasionally drop it.
- */
- struct rw_semaphore i_mmap_sem;
struct inode vfs_inode;
struct jbd2_inode *jinode;

@@ -2962,7 +2953,6 @@ extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
extern int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
loff_t lstart, loff_t lend);
extern vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf);
-extern vm_fault_t ext4_filemap_fault(struct vm_fault *vmf);
extern qsize_t *ext4_get_reserved_space(struct inode *inode);
extern int ext4_get_projid(struct inode *inode, kprojid_t *projid);
extern void ext4_da_release_space(struct inode *inode, int to_free);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 77c84d6f1af6..194b8af2b31d 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4467,6 +4467,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
loff_t len, int mode)
{
struct inode *inode = file_inode(file);
+ struct address_space *mapping = file->f_mapping;
handle_t *handle = NULL;
unsigned int max_blocks;
loff_t new_size = 0;
@@ -4553,17 +4554,17 @@ static long ext4_zero_range(struct file *file, loff_t offset,
* Prevent page faults from reinstantiating pages we have
* released from page cache.
*/
- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(mapping);

ret = ext4_break_layouts(inode);
if (ret) {
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
goto out_mutex;
}

ret = ext4_update_disksize_before_punch(inode, offset, len);
if (ret) {
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
goto out_mutex;
}
/* Now release the pages and zero block aligned part of pages */
@@ -4572,7 +4573,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,

ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size,
flags);
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
if (ret)
goto out_mutex;
}
@@ -5214,6 +5215,7 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
{
struct super_block *sb = inode->i_sb;
+ struct address_space *mapping = inode->i_mapping;
ext4_lblk_t punch_start, punch_stop;
handle_t *handle;
unsigned int credits;
@@ -5267,7 +5269,7 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
* Prevent page faults from reinstantiating pages we have released from
* page cache.
*/
- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(mapping);

ret = ext4_break_layouts(inode);
if (ret)
@@ -5282,15 +5284,15 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
* Write tail of the last page before removed range since it will get
* removed from the page cache below.
*/
- ret = filemap_write_and_wait_range(inode->i_mapping, ioffset, offset);
+ ret = filemap_write_and_wait_range(mapping, ioffset, offset);
if (ret)
goto out_mmap;
/*
* Write data that will be shifted to preserve them when discarding
* page cache below. We are also protected from pages becoming dirty
- * by i_mmap_sem.
+ * by i_rwsem and invalidate_lock.
*/
- ret = filemap_write_and_wait_range(inode->i_mapping, offset + len,
+ ret = filemap_write_and_wait_range(mapping, offset + len,
LLONG_MAX);
if (ret)
goto out_mmap;
@@ -5343,7 +5345,7 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
ext4_journal_stop(handle);
ext4_fc_stop_ineligible(sb);
out_mmap:
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
out_mutex:
inode_unlock(inode);
return ret;
@@ -5360,6 +5362,7 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
static int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
{
struct super_block *sb = inode->i_sb;
+ struct address_space *mapping = inode->i_mapping;
handle_t *handle;
struct ext4_ext_path *path;
struct ext4_extent *extent;
@@ -5418,7 +5421,7 @@ static int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
* Prevent page faults from reinstantiating pages we have released from
* page cache.
*/
- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(mapping);

ret = ext4_break_layouts(inode);
if (ret)
@@ -5519,7 +5522,7 @@ static int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
ext4_journal_stop(handle);
ext4_fc_stop_ineligible(sb);
out_mmap:
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
out_mutex:
inode_unlock(inode);
return ret;
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 816dedcbd541..d3b4ed91aa68 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -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 @@ static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
/* 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,
};
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index fe6045a46599..ee6e69d6f949 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3950,20 +3950,19 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
return ret;
}

-static void ext4_wait_dax_page(struct ext4_inode_info *ei)
+static void ext4_wait_dax_page(struct inode *inode)
{
- up_write(&ei->i_mmap_sem);
+ filemap_invalidate_unlock(inode->i_mapping);
schedule();
- down_write(&ei->i_mmap_sem);
+ filemap_invalidate_lock(inode->i_mapping);
}

int ext4_break_layouts(struct inode *inode)
{
- struct ext4_inode_info *ei = EXT4_I(inode);
struct page *page;
int error;

- if (WARN_ON_ONCE(!rwsem_is_locked(&ei->i_mmap_sem)))
+ if (WARN_ON_ONCE(!rwsem_is_locked(&inode->i_mapping->invalidate_lock)))
return -EINVAL;

do {
@@ -3974,7 +3973,7 @@ int ext4_break_layouts(struct inode *inode)
error = ___wait_var_event(&page->_refcount,
atomic_read(&page->_refcount) == 1,
TASK_INTERRUPTIBLE, 0, 0,
- ext4_wait_dax_page(ei));
+ ext4_wait_dax_page(inode));
} while (error == 0);

return error;
@@ -4005,9 +4004,9 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)

ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
if (ext4_has_inline_data(inode)) {
- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(mapping);
ret = ext4_convert_inline_data(inode);
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
if (ret)
return ret;
}
@@ -4058,7 +4057,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
* Prevent page faults from reinstantiating pages we have released from
* page cache.
*/
- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(mapping);

ret = ext4_break_layouts(inode);
if (ret)
@@ -4131,7 +4130,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
out_stop:
ext4_journal_stop(handle);
out_dio:
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
out_mutex:
inode_unlock(inode);
return ret;
@@ -5426,11 +5425,11 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
inode_dio_wait(inode);
}

- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(inode->i_mapping);

rc = ext4_break_layouts(inode);
if (rc) {
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(inode->i_mapping);
goto err_out;
}

@@ -5506,7 +5505,7 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
error = rc;
}
out_mmap_sem:
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(inode->i_mapping);
}

if (!error) {
@@ -5983,10 +5982,10 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
* data (and journalled aops don't know how to handle these cases).
*/
if (val) {
- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(inode->i_mapping);
err = filemap_write_and_wait(inode->i_mapping);
if (err < 0) {
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(inode->i_mapping);
return err;
}
}
@@ -6019,7 +6018,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
percpu_up_write(&sbi->s_writepages_rwsem);

if (val)
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(inode->i_mapping);

/* Finally we can mark the inode as dirty. */

@@ -6063,7 +6062,7 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
sb_start_pagefault(inode->i_sb);
file_update_time(vma->vm_file);

- down_read(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock_shared(mapping);

err = ext4_convert_inline_data(inode);
if (err)
@@ -6176,7 +6175,7 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
out_ret:
ret = block_page_mkwrite_return(err);
out:
- up_read(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock_shared(mapping);
sb_end_pagefault(inode->i_sb);
return ret;
out_error:
@@ -6184,15 +6183,3 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
ext4_journal_stop(handle);
goto out;
}
-
-vm_fault_t ext4_filemap_fault(struct vm_fault *vmf)
-{
- struct inode *inode = file_inode(vmf->vma->vm_file);
- vm_fault_t ret;
-
- down_read(&EXT4_I(inode)->i_mmap_sem);
- ret = filemap_fault(vmf);
- up_read(&EXT4_I(inode)->i_mmap_sem);
-
- return ret;
-}
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 31627f7dc5cd..c5ed562b4185 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -148,7 +148,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
goto journal_err_out;
}

- down_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_lock(inode->i_mapping);
err = filemap_write_and_wait(inode->i_mapping);
if (err)
goto err_out;
@@ -256,7 +256,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
ext4_double_up_write_data_sem(inode, inode_bl);

err_out:
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(inode->i_mapping);
journal_err_out:
unlock_two_nondirectories(inode, inode_bl);
iput(inode_bl);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7dc94f3e18e6..966fd5ca48e0 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -90,12 +90,9 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb,
/*
* Lock ordering
*
- * Note the difference between i_mmap_sem (EXT4_I(inode)->i_mmap_sem) and
- * i_mmap_rwsem (inode->i_mmap_rwsem)!
- *
* page fault path:
- * mmap_lock -> sb_start_pagefault -> i_mmap_sem (r) -> transaction start ->
- * page lock -> i_data_sem (rw)
+ * mmap_lock -> sb_start_pagefault -> invalidate_lock (r) -> transaction start
+ * -> page lock -> i_data_sem (rw)
*
* buffered write path:
* sb_start_write -> i_mutex -> mmap_lock
@@ -103,8 +100,9 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb,
* i_data_sem (rw)
*
* truncate:
- * sb_start_write -> i_mutex -> i_mmap_sem (w) -> i_mmap_rwsem (w) -> page lock
- * sb_start_write -> i_mutex -> i_mmap_sem (w) -> transaction start ->
+ * sb_start_write -> i_mutex -> invalidate_lock (w) -> i_mmap_rwsem (w) ->
+ * page lock
+ * sb_start_write -> i_mutex -> invalidate_lock (w) -> transaction start ->
* i_data_sem (rw)
*
* direct IO:
@@ -1350,7 +1348,6 @@ static void init_once(void *foo)
INIT_LIST_HEAD(&ei->i_orphan);
init_rwsem(&ei->xattr_sem);
init_rwsem(&ei->i_data_sem);
- init_rwsem(&ei->i_mmap_sem);
inode_init_once(&ei->vfs_inode);
ext4_fc_init_inode(&ei->vfs_inode);
}
diff --git a/fs/ext4/truncate.h b/fs/ext4/truncate.h
index bcbe3668c1d4..ce84aa2786c7 100644
--- a/fs/ext4/truncate.h
+++ b/fs/ext4/truncate.h
@@ -11,14 +11,16 @@
*/
static inline void ext4_truncate_failed_write(struct inode *inode)
{
+ struct address_space *mapping = inode->i_mapping;
+
/*
* We don't need to call ext4_break_layouts() because the blocks we
* are truncating were never visible to userspace.
*/
- down_write(&EXT4_I(inode)->i_mmap_sem);
- truncate_inode_pages(inode->i_mapping, inode->i_size);
+ filemap_invalidate_lock(mapping);
+ truncate_inode_pages(mapping, inode->i_size);
ext4_truncate(inode);
- up_write(&EXT4_I(inode)->i_mmap_sem);
+ filemap_invalidate_unlock(mapping);
}

/*
--
2.26.2