7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Norbert Szetei [ Upstream commit d84d6c1a7f1e2de9e601703a326a4c1b7b421943 ] When an exchange covers both files from offset 0 to i_disk_size, xmi_can_exchange_reflink_flags() assumes every mapping moved and hands the reflink flag over to the other file. That assumption is wrong. A file can still own shared blocks past i_disk_size, e.g. after EXCHANGE_RANGE_TO_EOF sets a smaller size without unmapping anything. The flag is cleared anyway, and the next write to such a block happens in place instead of CoW, corrupting the other file that shares it. Commit a23eca88448e ("xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN") fixed one instance of this. Rather than add another special case, stop moving the flags. xfs_exchmaps_ensure_reflink() already sets the flag on both inodes before the exchange, so both just keep it. Nothing sets CLEAR_INO{1,2}_REFLINK anymore. Intents logged by older kernels may still carry them; recovery already masks them off, so they stay in the log format mask and are ignored. XFS_IOC_SWAPEXT has the same problem: it moves the reflink flag from one inode to the other along with the extents. Just removing that is not enough here: the exchange path flags both inodes up front in xfs_exchmaps_ensure_reflink(), but swapext has no such step, so the inode receiving the shared extents would be left without the flag. Set it on both inodes instead, and make sure both have a CoW fork, since an inode with the reflink flag is expected to have one. The flag now stays until FALLOC_FL_UNSHARE_RANGE, xfs_scrub, or a truncate to zero removes it. Fixes: 966ceafc7a43 ("xfs: create deferred log items for file mapping exchanges") Fixes: f0bc4d134b46 ("xfs: swap inode reflink flags when swapping inode extents") Cc: stable@vger.kernel.org # v6.10 Assisted-by: LLM Signed-off-by: Norbert Szetei Reviewed-by: Dave Chinner Reviewed-by: Darrick J. Wong Signed-off-by: Carlos Maiolino [ sashal: Removed an extra duplicate INO1_WRITTEN guard when deleting xmi_can_exchange_reflink_flags(). ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/xfs/libxfs/xfs_exchmaps.c | 90 +---------------------------------------- fs/xfs/libxfs/xfs_log_format.h | 4 - fs/xfs/xfs_bmap_util.c | 15 ++---- 3 files changed, 10 insertions(+), 99 deletions(-) --- a/fs/xfs/libxfs/xfs_exchmaps.c +++ b/fs/xfs/libxfs/xfs_exchmaps.c @@ -49,7 +49,7 @@ struct xfs_exchmaps_adjacent { .right2 = { .br_startblock = HOLESTARTBLOCK }, \ } -/* Information to reset reflink flag / CoW fork state after an exchange. */ +/* Information to reset CoW fork state after an exchange. */ /* * If the reflink flag is set on either inode, make sure it has an incore CoW @@ -127,9 +127,7 @@ xmi_has_more_exchange_work(const struct static inline bool xmi_has_postop_work(const struct xfs_exchmaps_intent *xmi) { - return xmi->xmi_flags & (XFS_EXCHMAPS_CLEAR_INO1_REFLINK | - XFS_EXCHMAPS_CLEAR_INO2_REFLINK | - __XFS_EXCHMAPS_INO2_SHORTFORM); + return xmi->xmi_flags & __XFS_EXCHMAPS_INO2_SHORTFORM; } /* Check all mappings to make sure we can actually exchange them. */ @@ -525,18 +523,6 @@ free: return error; } -/* Clear the reflink flag after an exchange. */ -static inline void -xfs_exchmaps_clear_reflink( - struct xfs_trans *tp, - struct xfs_inode *ip) -{ - trace_xfs_reflink_unset_inode_flag(ip); - - ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK; - xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); -} - /* Finish whatever work might come after an exchange operation. */ static int xfs_exchmaps_do_postop_work( @@ -557,16 +543,6 @@ xfs_exchmaps_do_postop_work( return error; } - if (xmi->xmi_flags & XFS_EXCHMAPS_CLEAR_INO1_REFLINK) { - xfs_exchmaps_clear_reflink(tp, xmi->xmi_ip1); - xmi->xmi_flags &= ~XFS_EXCHMAPS_CLEAR_INO1_REFLINK; - } - - if (xmi->xmi_flags & XFS_EXCHMAPS_CLEAR_INO2_REFLINK) { - xfs_exchmaps_clear_reflink(tp, xmi->xmi_ip2); - xmi->xmi_flags &= ~XFS_EXCHMAPS_CLEAR_INO2_REFLINK; - } - return 0; } @@ -948,56 +924,13 @@ xfs_exchmaps_intent_destroy_cache(void) } /* - * Decide if we will exchange the reflink flags between the two files after the - * exchange. The only time we want to do this is if we're exchanging all - * mappings under EOF and the inode reflink flags have different states. + * Allocate and initialize a new incore intent item from a request. */ -static inline bool -xmi_can_exchange_reflink_flags( - const struct xfs_exchmaps_req *req, - unsigned int reflink_state) -{ - struct xfs_mount *mp = req->ip1->i_mount; - - /* - * The INO1_WRITTEN optimization can skip exchanging hole and - * unwritten mappings, which means we cannot guarantee that all - * shared extents actually moved to the other file. Clearing the - * reflink flag of an inode that still holds shared extents breaks - * the CoW write path, so refuse to exchange the flags in that case. - */ - if (req->flags & XFS_EXCHMAPS_INO1_WRITTEN) - return false; - - /* - * The INO1_WRITTEN optimization can skip exchanging hole and - * unwritten mappings, which means we cannot guarantee that all - * shared extents actually moved to the other file. Clearing the - * reflink flag of an inode that still holds shared extents breaks - * the CoW write path, so refuse to exchange the flags in that case. - */ - if (req->flags & XFS_EXCHMAPS_INO1_WRITTEN) - return false; - - if (hweight32(reflink_state) != 1) - return false; - if (req->startoff1 != 0 || req->startoff2 != 0) - return false; - if (req->blockcount != XFS_B_TO_FSB(mp, req->ip1->i_disk_size)) - return false; - if (req->blockcount != XFS_B_TO_FSB(mp, req->ip2->i_disk_size)) - return false; - return true; -} - - -/* Allocate and initialize a new incore intent item from a request. */ struct xfs_exchmaps_intent * xfs_exchmaps_init_intent( const struct xfs_exchmaps_req *req) { struct xfs_exchmaps_intent *xmi; - unsigned int rs = 0; xmi = kmem_cache_zalloc(xfs_exchmaps_intent_cache, GFP_NOFS | __GFP_NOFAIL); @@ -1021,23 +954,6 @@ xfs_exchmaps_init_intent( xmi->xmi_isize2 = req->ip1->i_disk_size; } - /* Record the state of each inode's reflink flag before the op. */ - if (xfs_is_reflink_inode(req->ip1)) - rs |= 1; - if (xfs_is_reflink_inode(req->ip2)) - rs |= 2; - - /* - * Figure out if we're clearing the reflink flags (which effectively - * exchanges them) after the operation. - */ - if (xmi_can_exchange_reflink_flags(req, rs)) { - if (rs & 1) - xmi->xmi_flags |= XFS_EXCHMAPS_CLEAR_INO1_REFLINK; - if (rs & 2) - xmi->xmi_flags |= XFS_EXCHMAPS_CLEAR_INO2_REFLINK; - } - if (S_ISDIR(VFS_I(xmi->xmi_ip2)->i_mode) || S_ISLNK(VFS_I(xmi->xmi_ip2)->i_mode)) xmi->xmi_flags |= __XFS_EXCHMAPS_INO2_SHORTFORM; --- a/fs/xfs/libxfs/xfs_log_format.h +++ b/fs/xfs/libxfs/xfs_log_format.h @@ -927,10 +927,8 @@ struct xfs_xmi_log_format { */ #define XFS_EXCHMAPS_INO1_WRITTEN (1ULL << 2) -/* Clear the reflink flag from inode1 after the operation. */ +/* No longer set, but older intents may carry them; keep them valid. */ #define XFS_EXCHMAPS_CLEAR_INO1_REFLINK (1ULL << 3) - -/* Clear the reflink flag from inode2 after the operation. */ #define XFS_EXCHMAPS_CLEAR_INO2_REFLINK (1ULL << 4) #define XFS_EXCHMAPS_LOGGED_FLAGS (XFS_EXCHMAPS_ATTR_FORK | \ --- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -1514,7 +1514,6 @@ xfs_swap_extents( struct xfs_bstat *sbp = &sxp->sx_stat; int src_log_flags, target_log_flags; int error = 0; - uint64_t f; int resblks = 0; unsigned int flags = 0; struct timespec64 ctime, mtime; @@ -1670,14 +1669,12 @@ xfs_swap_extents( if (error) goto out_trans_cancel; - /* Do we have to swap reflink flags? */ - if ((ip->i_diflags2 & XFS_DIFLAG2_REFLINK) ^ - (tip->i_diflags2 & XFS_DIFLAG2_REFLINK)) { - f = ip->i_diflags2 & XFS_DIFLAG2_REFLINK; - ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK; - ip->i_diflags2 |= tip->i_diflags2 & XFS_DIFLAG2_REFLINK; - tip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK; - tip->i_diflags2 |= f & XFS_DIFLAG2_REFLINK; + /* Either inode may now own shared blocks; flag both, with CoW forks. */ + if ((ip->i_diflags2 | tip->i_diflags2) & XFS_DIFLAG2_REFLINK) { + ip->i_diflags2 |= XFS_DIFLAG2_REFLINK; + tip->i_diflags2 |= XFS_DIFLAG2_REFLINK; + xfs_ifork_init_cow(ip); + xfs_ifork_init_cow(tip); } /* Swap the cow forks. */