| Message ID | b58782fcf631b6248174fb69f3314fd60b760404.1572255426.git.mbobrowski@mbobrowski.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ext4: port direct I/O to iomap infrastructure | expand |
On 10/28/19 4:23 PM, Matthew Bobrowski wrote: > 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> Thanks for the patch. Looks good to me. You may add: Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com> > --- > > Thanks Jan and Christoph for the suggestion on this one, highly > appreciated. > > fs/ext4/fsync.c | 72 ++++++++++++++++++++++++++++++++----------------- > 1 file 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; >
On Mon 28-10-19 21:53:52, Matthew Bobrowski wrote: > 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> Nice! You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > > Thanks Jan and Christoph for the suggestion on this one, highly > appreciated. > > fs/ext4/fsync.c | 72 ++++++++++++++++++++++++++++++++----------------- > 1 file 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; > -- > 2.20.1 >
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;
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> --- Thanks Jan and Christoph for the suggestion on this one, highly appreciated. fs/ext4/fsync.c | 72 ++++++++++++++++++++++++++++++++----------------- 1 file changed, 47 insertions(+), 25 deletions(-)