kernel/git/stable/linux.git/fs/gfs2, branch linux-5.18.y

gfs2: use i_lock spin_lock for inode qadata

2022-06-09T08:29:47+00:00

[ Upstream commit 5fcff61eea9efd1f4b60e89d2d686b5feaea100f ] Before this patch, functions gfs2_qa_get and _put used the i_rw_mutex to prevent simultaneous access to its i_qadata. But i_rw_mutex is now used for many other things, including iomap_begin and end, which causes a conflict according to lockdep. We cannot just remove the lock since simultaneous opens (gfs2_open -> gfs2_open_common -> gfs2_qa_get) can then stomp on each others values for i_qadata. This patch solves the conflict by using the i_lock spin_lock in the inode to prevent simultaneous access. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin

gfs2: Stop using glock holder auto-demotion for now

2022-05-13T20:32:52+00:00

We're having unresolved issues with the glock holder auto-demotion mechanism introduced in commit dc732906c245. This mechanism was assumed to be essential for avoiding frequent short reads and writes until commit 296abc0d91d8 ("gfs2: No short reads or writes upon glock contention"). Since then, when the inode glock is lost, it is simply re-acquired and the operation is resumed. This means that apart from the performance penalty, we might as well drop the inode glock before faulting in pages, and re-acquire it afterwards. Signed-off-by: Andreas Gruenbacher

gfs2: buffered write prefaulting

2022-05-13T20:32:52+00:00

In gfs2_file_buffered_write, to increase the likelihood that all the user memory we're trying to write will be resident in memory, carry out the write in chunks and fault in each chunk of user memory before trying to write it. Otherwise, some workloads will trigger frequent short "internal" writes, causing filesystem blocks to be allocated and then partially deallocated again when writing into holes, which is wasteful and breaks reservations. Neither the chunked writes nor any of the short "internal" writes are user visible. Signed-off-by: Andreas Gruenbacher

gfs2: Align read and write chunks to the page cache

2022-05-13T20:00:22+00:00

Align the chunks that reads and writes are carried out in to the page cache rather than the user buffers. This will be more efficient in general, especially for allocating writes. Optimizing the case that the user buffer is gfs2 backed isn't very useful; we only need to make sure we won't deadlock. Signed-off-by: Andreas Gruenbacher

gfs2: Pull return value test out of should_fault_in_pages

2022-05-13T20:00:22+00:00

Pull the return value test of the previous read or write operation out of should_fault_in_pages(). In a following patch, we'll fault in pages before the I/O and there will be no return value to check. Signed-off-by: Andreas Gruenbacher

gfs2: Clean up use of fault_in_iov_iter_{read,write}able

2022-05-13T20:00:22+00:00

No need to store the return value of the fault_in functions in separate variables. Signed-off-by: Andreas Gruenbacher

gfs2: Variable rename

2022-05-13T20:00:22+00:00

Instead of counting the number of bytes read from the filesystem, functions gfs2_file_direct_read and gfs2_file_read_iter count the number of bytes written into the user buffer. Conversely, functions gfs2_file_direct_write and gfs2_file_buffered_write count the number of bytes read from the user buffer. This is nothing but confusing, so change the read functions to count how many bytes they have read, and the write functions to count how many bytes they have written. Signed-off-by: Andreas Gruenbacher

gfs2: Fix filesystem block deallocation for short writes

2022-05-13T19:59:18+00:00

When a write cannot be carried out in full, gfs2_iomap_end() releases blocks that have been allocated for this write but haven't been used. To compute the end of the allocation, gfs2_iomap_end() incorrectly rounded the end of the attempted write down to the next block boundary to arrive at the end of the allocation. It would have to round up, but the end of the allocation is also available as iomap->offset + iomap->length, so just use that instead. In addition, use round_up() for computing the start of the unused range. Fixes: 64bc06bb32ee ("gfs2: iomap buffered write support") Signed-off-by: Andreas Gruenbacher

gfs2: No short reads or writes upon glock contention

2022-04-28T13:14:48+00:00

Commit 00bfe02f4796 ("gfs2: Fix mmap + page fault deadlocks for buffered I/O") changed gfs2_file_read_iter() and gfs2_file_buffered_write() to allow dropping the inode glock while faulting in user buffers. When the lock was dropped, a short result was returned to indicate that the operation was interrupted. As pointed out by Linus (see the link below), this behavior is broken and the operations should always re-acquire the inode glock and resume the operation instead. Link: https://lore.kernel.org/lkml/CAHk-=whaz-g_nOOoo8RRiWNjnv2R+h6_xk2F1J4TuSRxk1MtLw@mail.gmail.com/ Fixes: 00bfe02f4796 ("gfs2: Fix mmap + page fault deadlocks for buffered I/O") Signed-off-by: Andreas Gruenbacher

gfs2: Don't re-check for write past EOF unnecessarily

2022-04-26T13:38:00+00:00

Only re-check for direct I/O writes past the end of the file after re-acquiring the inode glock. Signed-off-by: Andreas Gruenbacher