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authorMatthew Bobrowski <mbobrowski@mbobrowski.org>2019-11-05 23:02:23 +1100
committerTheodore Ts'o <tytso@mit.edu>2019-11-05 11:31:40 -0500
commit3eaf9cc62f447a742b26fa601993e94406aa1ea1 (patch)
tree5256bb4a4e7e8dc9af54b790a11e90927b50f5fe /fs/ext4
parent0b9f230b94dd7457802264dc4c16921b3527dcf1 (diff)
ext4: update ext4_sync_file() to not use __generic_file_fsync()
When the filesystem is created without a journal, we eventually call into __generic_file_fsync() in order to write out all the modified in-core data to the permanent storage device. This function happens to try and obtain an inode_lock() while synchronizing the files buffer and it's associated metadata. Generally, this is fine, however it becomes a problem when there is higher level code that has already obtained an inode_lock() as this leads to a recursive lock situation. This case is especially true when porting across direct I/O to iomap infrastructure as we obtain an inode_lock() early on in the I/O within ext4_dio_write_iter() and hold it until the I/O has been completed. Consequently, to not run into this specific issue, we move away from calling into __generic_file_fsync() and perform the necessary synchronization tasks within ext4_sync_file(). Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org> Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/3495f35ef67f2021b567e28e6f59222e583689b8.1572949325.git.mbobrowski@mbobrowski.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/fsync.c72
1 files changed, 47 insertions, 25 deletions
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 5508baa11bb6..e10206e7f4bb 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -80,6 +80,43 @@ static int ext4_sync_parent(struct inode *inode)
return ret;
}
+static int ext4_fsync_nojournal(struct inode *inode, bool datasync,
+ bool *needs_barrier)
+{
+ int ret, err;
+
+ ret = sync_mapping_buffers(inode->i_mapping);
+ if (!(inode->i_state & I_DIRTY_ALL))
+ return ret;
+ if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
+ return ret;
+
+ err = sync_inode_metadata(inode, 1);
+ if (!ret)
+ ret = err;
+
+ if (!ret)
+ ret = ext4_sync_parent(inode);
+ if (test_opt(inode->i_sb, BARRIER))
+ *needs_barrier = true;
+
+ return ret;
+}
+
+static int ext4_fsync_journal(struct inode *inode, bool datasync,
+ bool *needs_barrier)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+ tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
+
+ if (journal->j_flags & JBD2_BARRIER &&
+ !jbd2_trans_will_send_data_barrier(journal, commit_tid))
+ *needs_barrier = true;
+
+ return jbd2_complete_transaction(journal, commit_tid);
+}
+
/*
* akpm: A new design for ext4_sync_file().
*
@@ -91,17 +128,14 @@ static int ext4_sync_parent(struct inode *inode)
* What we do is just kick off a commit and wait on it. This will snapshot the
* inode to disk.
*/
-
int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
{
- struct inode *inode = file->f_mapping->host;
- struct ext4_inode_info *ei = EXT4_I(inode);
- journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
int ret = 0, err;
- tid_t commit_tid;
bool needs_barrier = false;
+ struct inode *inode = file->f_mapping->host;
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
- if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+ if (unlikely(ext4_forced_shutdown(sbi)))
return -EIO;
J_ASSERT(ext4_journal_current_handle() == NULL);
@@ -111,23 +145,15 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
if (sb_rdonly(inode->i_sb)) {
/* Make sure that we read updated s_mount_flags value */
smp_rmb();
- if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
+ if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)
ret = -EROFS;
goto out;
}
- if (!journal) {
- ret = __generic_file_fsync(file, start, end, datasync);
- if (!ret)
- ret = ext4_sync_parent(inode);
- if (test_opt(inode->i_sb, BARRIER))
- goto issue_flush;
- goto out;
- }
-
ret = file_write_and_wait_range(file, start, end);
if (ret)
return ret;
+
/*
* data=writeback,ordered:
* The caller's filemap_fdatawrite()/wait will sync the data.
@@ -142,18 +168,14 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
* (they were dirtied by commit). But that's OK - the blocks are
* safe in-journal, which is all fsync() needs to ensure.
*/
- if (ext4_should_journal_data(inode)) {
+ if (!sbi->s_journal)
+ ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier);
+ else if (ext4_should_journal_data(inode))
ret = ext4_force_commit(inode->i_sb);
- goto out;
- }
+ else
+ ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
- commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
- if (journal->j_flags & JBD2_BARRIER &&
- !jbd2_trans_will_send_data_barrier(journal, commit_tid))
- needs_barrier = true;
- ret = jbd2_complete_transaction(journal, commit_tid);
if (needs_barrier) {
- issue_flush:
err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
if (!ret)
ret = err;