lwn.git/fs/xfs/xfs_bmap_util.c, branch docs-5.3

xfs: add missing error check in xfs_prepare_shift()

2019-04-26T19:28:56+00:00

xfs_prepare_shift() fails to check the error return from xfs_flush_unmap_range(). If the latter fails, that could lead to an insert/collapse range operation over a delalloc range, which is not supported. Add an error check and return appropriately. This is reproduced rarely by generic/475. Fixes: 7f9f71be84bc ("xfs: extent shifting doesn't fully invalidate page cache") Signed-off-by: Brian Foster Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Reviewed-by: Allison Collins Reviewed-by: Dave Chinner

xfs: introduce an always_cow mode

2019-02-21T15:55:07+00:00

Add a mode where XFS never overwrites existing blocks in place. This is to aid debugging our COW code, and also put infatructure in place for things like possible future support for zoned block devices, which can't support overwrites. This mode is enabled globally by doing a: echo 1 > /sys/fs/xfs/debug/always_cow Note that the parameter is global to allow running all tests in xfstests easily in this mode, which would not easily be possible with a per-fs sysfs file. In always_cow mode persistent preallocations are disabled, and fallocate will fail when called with a 0 mode (with our without FALLOC_FL_KEEP_SIZE), and not create unwritten extent for zeroed space when called with FALLOC_FL_ZERO_RANGE or FALLOC_FL_UNSHARE_RANGE. There are a few interesting xfstests failures when run in always_cow mode: - generic/392 fails because the bytes used in the file used to test hole punch recovery are less after the log replay. This is because the blocks written and then punched out are only freed with a delay due to the logging mechanism. - xfs/170 will fail as the already fragile file streams mechanism doesn't seem to interact well with the COW allocator - xfs/180 xfs/182 xfs/192 xfs/198 xfs/204 and xfs/208 will claim the file system is badly fragmented, but there is not much we can do to avoid that when always writing out of place - xfs/205 fails because overwriting a file in always_cow mode will require new space allocation and the assumption in the test thus don't work anymore. - xfs/326 fails to modify the file at all in always_cow mode after injecting the refcount error, leading to an unexpected md5sum after the remount, but that again is expected Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

xfs: fix PAGE_MASK usage in xfs_free_file_space

2018-12-04T16:50:49+00:00

In commit e53c4b598, I *tried* to teach xfs to force writeback when we fzero/fpunch right up to EOF so that if EOF is in the middle of a page, the post-EOF part of the page gets zeroed before we return to userspace. Unfortunately, I missed the part where PAGE_MASK is ~(PAGE_SIZE - 1), which means that we totally fail to zero if we're fpunching and EOF is within the first page. Worse yet, the same PAGE_MASK thinko plagues the filemap_write_and_wait_range call, so we'd initiate writeback of the entire file, which (mostly) masked the thinko. Drop the tricky PAGE_MASK and replace it with correct usage of PAGE_SIZE and the proper rounding macros. Fixes: e53c4b598 ("xfs: ensure post-EOF zeroing happens after zeroing part of a file") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Reviewed-by: Christoph Hellwig

xfs: flush removing page cache in xfs_reflink_remap_prep

2018-11-21T18:10:53+00:00

On a sub-page block size filesystem, fsx is failing with a data corruption after a series of operations involving copying a file with the destination offset beyond EOF of the destination of the file: 8093(157 mod 256): TRUNCATE DOWN from 0x7a120 to 0x50000 ******WWWW 8094(158 mod 256): INSERT 0x25000 thru 0x25fff (0x1000 bytes) 8095(159 mod 256): COPY 0x18000 thru 0x1afff (0x3000 bytes) to 0x2f400 8096(160 mod 256): WRITE 0x5da00 thru 0x651ff (0x7800 bytes) HOLE 8097(161 mod 256): COPY 0x2000 thru 0x5fff (0x4000 bytes) to 0x6fc00 The second copy here is beyond EOF, and it is to sub-page (4k) but block aligned (1k) offset. The clone runs the EOF zeroing, landing in a pre-existing post-eof delalloc extent. This zeroes the post-eof extents in the page cache just fine, dirtying the pages correctly. The problem is that xfs_reflink_remap_prep() now truncates the page cache over the range that it is copying it to, and rounds that down to cover the entire start page. This removes the dirty page over the delalloc extent from the page cache without having written it back. Hence later, when the page cache is flushed, the page at offset 0x6f000 has not been written back and hence exposes stale data, which fsx trips over less than 10 operations later. Fix this by changing xfs_reflink_remap_prep() to use xfs_flush_unmap_range(). Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

xfs: extent shifting doesn't fully invalidate page cache

2018-11-20T18:36:19+00:00

The extent shifting code uses a flush and invalidate mechainsm prior to shifting extents around. This is similar to what xfs_free_file_space() does, but it doesn't take into account things like page cache vs block size differences, and it will fail if there is a page that it currently busy. xfs_flush_unmap_range() handles all of these cases, so just convert xfs_prepare_shift() to us that mechanism rather than having it's own special sauce. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

xfs: cancel COW blocks before swapext

2018-10-18T06:21:55+00:00

We need to make sure we have no outstanding COW blocks before we swap extents, as there is nothing preventing us from having preallocated COW delalloc on either inode that swapext is called on. That case can easily be reproduced by running generic/324 in always_cow mode: [ 620.760572] XFS: Assertion failed: tip->i_delayed_blks == 0, file: fs/xfs/xfs_bmap_util.c, line: 1669 [ 620.761608] ------------[ cut here ]------------ [ 620.762171] kernel BUG at fs/xfs/xfs_message.c:102! [ 620.762732] invalid opcode: 0000 [#1] SMP PTI [ 620.763272] CPU: 0 PID: 24153 Comm: xfs_fsr Tainted: G W 4.19.0-rc1+ #4182 [ 620.764203] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014 [ 620.765202] RIP: 0010:assfail+0x20/0x28 [ 620.765646] Code: 31 ff e8 83 fc ff ff 0f 0b c3 48 89 f1 41 89 d0 48 c7 c6 48 ca 8d 82 48 89 fa 38 [ 620.767758] RSP: 0018:ffffc9000898bc10 EFLAGS: 00010202 [ 620.768359] RAX: 0000000000000000 RBX: ffff88012f14ba40 RCX: 0000000000000000 [ 620.769174] RDX: 00000000ffffffc0 RSI: 000000000000000a RDI: ffffffff828560d9 [ 620.769982] RBP: ffff88012f14b300 R08: 0000000000000000 R09: 0000000000000000 [ 620.770788] R10: 000000000000000a R11: f000000000000000 R12: ffffc9000898bc98 [ 620.771638] R13: ffffc9000898bc9c R14: ffff880130b5e2b8 R15: ffff88012a1fa2a8 [ 620.772504] FS: 00007fdc36e0fbc0(0000) GS:ffff88013ba00000(0000) knlGS:0000000000000000 [ 620.773475] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 620.774168] CR2: 00007fdc3604d000 CR3: 0000000132afc000 CR4: 00000000000006f0 [ 620.774978] Call Trace: [ 620.775274] xfs_swap_extent_forks+0x2a0/0x2e0 [ 620.775792] xfs_swap_extents+0x38b/0xab0 [ 620.776256] xfs_ioc_swapext+0x121/0x140 [ 620.776709] xfs_file_ioctl+0x328/0xc90 [ 620.777154] ? rcu_read_lock_sched_held+0x50/0x60 [ 620.777694] ? xfs_iunlock+0x233/0x260 [ 620.778127] ? xfs_setattr_nonsize+0x3be/0x6a0 [ 620.778647] do_vfs_ioctl+0x9d/0x680 [ 620.779071] ? ksys_fchown+0x47/0x80 [ 620.779552] ksys_ioctl+0x35/0x70 [ 620.780040] __x64_sys_ioctl+0x11/0x20 [ 620.780530] do_syscall_64+0x4b/0x190 [ 620.780927] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 620.781467] RIP: 0033:0x7fdc364d0f07 [ 620.781900] Code: b3 66 90 48 8b 05 81 5f 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 28 [ 620.784044] RSP: 002b:00007ffe2a766038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 620.784896] RAX: ffffffffffffffda RBX: 0000000000000025 RCX: 00007fdc364d0f07 [ 620.785667] RDX: 0000560296ca2fc0 RSI: 00000000c0c0586d RDI: 0000000000000005 [ 620.786398] RBP: 0000000000000025 R08: 0000000000001200 R09: 0000000000000000 [ 620.787283] R10: 0000000000000432 R11: 0000000000000246 R12: 0000000000000005 [ 620.788051] R13: 0000000000000000 R14: 0000000000001000 R15: 0000000000000006 [ 620.788927] Modules linked in: [ 620.789340] ---[ end trace 9503b7417ffdbdb0 ]--- [ 620.790065] RIP: 0010:assfail+0x20/0x28 [ 620.790642] Code: 31 ff e8 83 fc ff ff 0f 0b c3 48 89 f1 41 89 d0 48 c7 c6 48 ca 8d 82 48 89 fa 38 [ 620.793038] RSP: 0018:ffffc9000898bc10 EFLAGS: 00010202 [ 620.793609] RAX: 0000000000000000 RBX: ffff88012f14ba40 RCX: 0000000000000000 [ 620.794317] RDX: 00000000ffffffc0 RSI: 000000000000000a RDI: ffffffff828560d9 [ 620.795025] RBP: ffff88012f14b300 R08: 0000000000000000 R09: 0000000000000000 [ 620.795778] R10: 000000000000000a R11: f000000000000000 R12: ffffc9000898bc98 [ 620.796675] R13: ffffc9000898bc9c R14: ffff880130b5e2b8 R15: ffff88012a1fa2a8 [ 620.797782] FS: 00007fdc36e0fbc0(0000) GS:ffff88013ba00000(0000) knlGS:0000000000000000 [ 620.798908] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 620.799594] CR2: 00007fdc3604d000 CR3: 0000000132afc000 CR4: 00000000000006f0 [ 620.800424] Kernel panic - not syncing: Fatal exception [ 620.801191] Kernel Offset: disabled [ 620.801597] ---[ end Kernel panic - not syncing: Fatal exception ]--- Signed-off-by: Christoph Hellwig Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner

xfs: remove the unused trimmed argument from xfs_reflink_trim_around_shared

2018-10-18T06:19:48+00:00

Signed-off-by: Christoph Hellwig Reviewed-by: Brian Foster Signed-off-by: Dave Chinner

xfs: remove suport for filesystems without unwritten extent flag

2018-10-18T06:18:58+00:00

The option to enable unwritten extents was made default in 2003, removed from mkfs in 2007, and cannot be disabled in v5. We also rely on it for a lot of common functionality, so filesystems without it will run a completely untested and buggy code path. Enabling the support also is a simple bit flip using xfs_db, so legacy file systems can still be brought forward. Signed-off-by: Christoph Hellwig Reviewed-by: Brian Foster Signed-off-by: Dave Chinner

xfs: don't bring in extents in xfs_bmap_punch_delalloc_range

2018-09-29T03:47:46+00:00

This function is only used to punch out delayed allocations on I/O failure, which means we need to have read the extents earlier. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Dave Chinner

xfs: remove last of unnecessary xfs_defer_cancel() callers

2018-09-29T03:41:58+00:00

Now that deferred operations are completely managed via transactions, it's no longer necessary to cancel the dfops in error paths that already cancel the associated transaction. There are a few such calls lingering throughout the codebase. Remove all remaining unnecessary calls to xfs_defer_cancel(). This leaves xfs_defer_cancel() calls in two places. The first is the call in the transaction cancel path itself, which facilitates this patch. The second is made via the xfs_defer_finish() error path to provide consistent error semantics with transaction commit. For example, xfs_trans_commit() expects an xfs_defer_finish() failure to clean up the dfops structure before it returns. Signed-off-by: Brian Foster Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner