From: Greg Kroah-Hartman Date: Tue, 18 Feb 2025 12:55:30 +0000 (+0100) Subject: 6.1-stable patches X-Git-Tag: v6.1.129~54 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0e2ad992444463b5181c8c2d25594198b88eab64;p=thirdparty%2Fkernel%2Fstable-queue.git 6.1-stable patches added patches: btrfs-fix-hole-expansion-when-writing-at-an-offset-beyond-eof.patch --- diff --git a/queue-6.1/btrfs-fix-hole-expansion-when-writing-at-an-offset-beyond-eof.patch b/queue-6.1/btrfs-fix-hole-expansion-when-writing-at-an-offset-beyond-eof.patch new file mode 100644 index 0000000000..8436a0553e --- /dev/null +++ b/queue-6.1/btrfs-fix-hole-expansion-when-writing-at-an-offset-beyond-eof.patch @@ -0,0 +1,103 @@ +From da2dccd7451de62b175fb8f0808d644959e964c7 Mon Sep 17 00:00:00 2001 +From: Filipe Manana +Date: Wed, 5 Feb 2025 17:36:48 +0000 +Subject: btrfs: fix hole expansion when writing at an offset beyond EOF + +From: Filipe Manana + +commit da2dccd7451de62b175fb8f0808d644959e964c7 upstream. + +At btrfs_write_check() if our file's i_size is not sector size aligned and +we have a write that starts at an offset larger than the i_size that falls +within the same page of the i_size, then we end up not zeroing the file +range [i_size, write_offset). + +The code is this: + + start_pos = round_down(pos, fs_info->sectorsize); + oldsize = i_size_read(inode); + if (start_pos > oldsize) { + /* Expand hole size to cover write data, preventing empty gap */ + loff_t end_pos = round_up(pos + count, fs_info->sectorsize); + + ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, end_pos); + if (ret) + return ret; + } + +So if our file's i_size is 90269 bytes and a write at offset 90365 bytes +comes in, we get 'start_pos' set to 90112 bytes, which is less than the +i_size and therefore we don't zero out the range [90269, 90365) by +calling btrfs_cont_expand(). + +This is an old bug introduced in commit 9036c10208e1 ("Btrfs: update hole +handling v2"), from 2008, and the buggy code got moved around over the +years. + +Fix this by discarding 'start_pos' and comparing against the write offset +('pos') without any alignment. + +This bug was recently exposed by test case generic/363 which tests this +scenario by polluting ranges beyond EOF with an mmap write and than verify +that after a file increases we get zeroes for the range which is supposed +to be a hole and not what we wrote with the previous mmaped write. + +We're only seeing this exposed now because generic/363 used to run only +on xfs until last Sunday's fstests update. + +The test was failing like this: + + $ ./check generic/363 + FSTYP -- btrfs + PLATFORM -- Linux/x86_64 debian0 6.13.0-rc7-btrfs-next-185+ #17 SMP PREEMPT_DYNAMIC Mon Feb 3 12:28:46 WET 2025 + MKFS_OPTIONS -- /dev/sdc + MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1 + + generic/363 0s ... [failed, exit status 1]- output mismatch (see /home/fdmanana/git/hub/xfstests/results//generic/363.out.bad) +# --- tests/generic/363.out 2025-02-05 15:31:14.013646509 +0000 +# +++ /home/fdmanana/git/hub/xfstests/results//generic/363.out.bad 2025-02-05 17:25:33.112630781 +0000 + @@ -1 +1,46 @@ + QA output created by 363 + +READ BAD DATA: offset = 0xdcad, size = 0xd921, fname = /home/fdmanana/btrfs-tests/dev/junk + +OFFSET GOOD BAD RANGE + +0x1609d 0x0000 0x3104 0x0 + +operation# (mod 256) for the bad data may be 4 + +0x1609e 0x0000 0x0472 0x1 + +operation# (mod 256) for the bad data may be 4 + ... + (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/generic/363.out /home/fdmanana/git/hub/xfstests/results//generic/363.out.bad' to see the entire diff) + Ran: generic/363 + Failures: generic/363 + Failed 1 of 1 tests + +Fixes: 9036c10208e1 ("Btrfs: update hole handling v2") +CC: stable@vger.kernel.org +Reviewed-by: Qu Wenruo +Signed-off-by: Filipe Manana +Signed-off-by: David Sterba +Signed-off-by: Greg Kroah-Hartman +--- + fs/btrfs/file.c | 4 +--- + 1 file changed, 1 insertion(+), 3 deletions(-) + +--- a/fs/btrfs/file.c ++++ b/fs/btrfs/file.c +@@ -1122,7 +1122,6 @@ static int btrfs_write_check(struct kioc + loff_t pos = iocb->ki_pos; + int ret; + loff_t oldsize; +- loff_t start_pos; + + /* + * Quickly bail out on NOWAIT writes if we don't have the nodatacow or +@@ -1147,9 +1146,8 @@ static int btrfs_write_check(struct kioc + */ + update_time_for_write(inode); + +- start_pos = round_down(pos, fs_info->sectorsize); + oldsize = i_size_read(inode); +- if (start_pos > oldsize) { ++ if (pos > oldsize) { + /* Expand hole size to cover write data, preventing empty gap */ + loff_t end_pos = round_up(pos + count, fs_info->sectorsize); + diff --git a/queue-6.1/series b/queue-6.1/series index afe99dfcd1..e194c77858 100644 --- a/queue-6.1/series +++ b/queue-6.1/series @@ -532,3 +532,4 @@ regmap-irq-add-missing-kfree.patch arm64-handle-.arm.attributes-section-in-linker-scripts.patch mmc-mtk-sd-fix-register-settings-for-hs400-es-mode.patch mlxsw-add-return-value-check-for-mlxsw_sp_port_get_stats_raw.patch +btrfs-fix-hole-expansion-when-writing-at-an-offset-beyond-eof.patch