From 4021e685139d567b3fc862f54101ae9dbb15d8b5 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Wed, 9 Oct 2024 11:31:50 +0800 Subject: [PATCH 1/7] fs/super.c: introduce get_tree_bdev_flags() As Allison reported [1], currently get_tree_bdev() will store "Can't lookup blockdev" error message. Although it makes sense for pure bdev-based fses, this message may mislead users who try to use EROFS file-backed mounts since get_tree_nodev() is used as a fallback then. Add get_tree_bdev_flags() to specify extensible flags [2] and GET_TREE_BDEV_QUIET_LOOKUP to silence "Can't lookup blockdev" message since it's misleading to EROFS file-backed mounts now. [1] https://lore.kernel.org/r/CAOYeF9VQ8jKVmpy5Zy9DNhO6xmWSKMB-DO8yvBB0XvBE7=3Ugg@mail.gmail.com [2] https://lore.kernel.org/r/ZwUkJEtwIpUA4qMz@infradead.org Suggested-by: Christoph Hellwig Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20241009033151.2334888-1-hsiangkao@linux.alibaba.com Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Christian Brauner --- fs/super.c | 26 ++++++++++++++++++++------ include/linux/fs_context.h | 6 ++++++ 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/fs/super.c b/fs/super.c index 1db230432960..c9c7223bc2a2 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1596,13 +1596,14 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, EXPORT_SYMBOL_GPL(setup_bdev_super); /** - * get_tree_bdev - Get a superblock based on a single block device + * get_tree_bdev_flags - Get a superblock based on a single block device * @fc: The filesystem context holding the parameters * @fill_super: Helper to initialise a new superblock + * @flags: GET_TREE_BDEV_* flags */ -int get_tree_bdev(struct fs_context *fc, - int (*fill_super)(struct super_block *, - struct fs_context *)) +int get_tree_bdev_flags(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc), unsigned int flags) { struct super_block *s; int error = 0; @@ -1613,10 +1614,10 @@ int get_tree_bdev(struct fs_context *fc, error = lookup_bdev(fc->source, &dev); if (error) { - errorf(fc, "%s: Can't lookup blockdev", fc->source); + if (!(flags & GET_TREE_BDEV_QUIET_LOOKUP)) + errorf(fc, "%s: Can't lookup blockdev", fc->source); return error; } - fc->sb_flags |= SB_NOSEC; s = sget_dev(fc, dev); if (IS_ERR(s)) @@ -1644,6 +1645,19 @@ int get_tree_bdev(struct fs_context *fc, fc->root = dget(s->s_root); return 0; } +EXPORT_SYMBOL_GPL(get_tree_bdev_flags); + +/** + * get_tree_bdev - Get a superblock based on a single block device + * @fc: The filesystem context holding the parameters + * @fill_super: Helper to initialise a new superblock + */ +int get_tree_bdev(struct fs_context *fc, + int (*fill_super)(struct super_block *, + struct fs_context *)) +{ + return get_tree_bdev_flags(fc, fill_super, 0); +} EXPORT_SYMBOL(get_tree_bdev); static int test_bdev_super(struct super_block *s, void *data) diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h index c13e99cbbf81..4b4bfef6f053 100644 --- a/include/linux/fs_context.h +++ b/include/linux/fs_context.h @@ -160,6 +160,12 @@ extern int get_tree_keyed(struct fs_context *fc, int setup_bdev_super(struct super_block *sb, int sb_flags, struct fs_context *fc); + +#define GET_TREE_BDEV_QUIET_LOOKUP 0x0001 +int get_tree_bdev_flags(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc), unsigned int flags); + extern int get_tree_bdev(struct fs_context *fc, int (*fill_super)(struct super_block *sb, struct fs_context *fc)); From 14c2d97265ea5989000c428dbb7321cbd4a85f9b Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Wed, 9 Oct 2024 11:31:51 +0800 Subject: [PATCH 2/7] erofs: use get_tree_bdev_flags() to avoid misleading messages Users can pass in an arbitrary source path for the proper type of a mount then without "Can't lookup blockdev" error message. Reported-by: Allison Karlitskaya Closes: https://lore.kernel.org/r/CAOYeF9VQ8jKVmpy5Zy9DNhO6xmWSKMB-DO8yvBB0XvBE7=3Ugg@mail.gmail.com Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20241009033151.2334888-2-hsiangkao@linux.alibaba.com Signed-off-by: Christian Brauner --- fs/erofs/super.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/erofs/super.c b/fs/erofs/super.c index 320d586c3896..bed3dbe5b7cb 100644 --- a/fs/erofs/super.c +++ b/fs/erofs/super.c @@ -709,7 +709,9 @@ static int erofs_fc_get_tree(struct fs_context *fc) if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && sbi->fsid) return get_tree_nodev(fc, erofs_fc_fill_super); - ret = get_tree_bdev(fc, erofs_fc_fill_super); + ret = get_tree_bdev_flags(fc, erofs_fc_fill_super, + IS_ENABLED(CONFIG_EROFS_FS_BACKED_BY_FILE) ? + GET_TREE_BDEV_QUIET_LOOKUP : 0); #ifdef CONFIG_EROFS_FS_BACKED_BY_FILE if (ret == -ENOTBLK) { if (!fc->source) From 6b51b9f65cec2c5246b06eec0334ba465ba357a8 Mon Sep 17 00:00:00 2001 From: Hongbo Li Date: Tue, 22 Oct 2024 09:38:12 +0800 Subject: [PATCH 3/7] doc: correcting the debug path for cachefiles The original debug path is under "/sys/modules", that's wrong. The real path in kernel is "/sys/module". So we can correct it. Signed-off-by: Hongbo Li Link: https://lore.kernel.org/r/20241022013812.2880883-1-lihongbo22@huawei.com Signed-off-by: Christian Brauner --- Documentation/filesystems/caching/cachefiles.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/filesystems/caching/cachefiles.rst b/Documentation/filesystems/caching/cachefiles.rst index e04a27bdbe19..b3ccc782cb3b 100644 --- a/Documentation/filesystems/caching/cachefiles.rst +++ b/Documentation/filesystems/caching/cachefiles.rst @@ -115,7 +115,7 @@ set up cache ready for use. The following script commands are available: This mask can also be set through sysfs, eg:: - echo 5 >/sys/modules/cachefiles/parameters/debug + echo 5 > /sys/module/cachefiles/parameters/debug Starting the Cache From 247d65fb122ad560be1c8c4d87d7374fb28b0770 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 23 Oct 2024 11:40:10 +0100 Subject: [PATCH 4/7] afs: Fix missing subdir edit when renamed between parent dirs When rename moves an AFS subdirectory between parent directories, the subdir also needs a bit of editing: the ".." entry needs updating to point to the new parent (though I don't make use of the info) and the DV needs incrementing by 1 to reflect the change of content. The server also sends a callback break notification on the subdirectory if we have one, but we can take care of recovering the promise next time we access the subdir. This can be triggered by something like: mount -t afs %example.com:xfstest.test20 /xfstest.test/ mkdir /xfstest.test/{aaa,bbb,aaa/ccc} touch /xfstest.test/bbb/ccc/d mv /xfstest.test/{aaa/ccc,bbb/ccc} touch /xfstest.test/bbb/ccc/e When the pathwalk for the second touch hits "ccc", kafs spots that the DV is incorrect and downloads it again (so the fix is not critical). Fix this, if the rename target is a directory and the old and new parents are different, by: (1) Incrementing the DV number of the target locally. (2) Editing the ".." entry in the target to refer to its new parent's vnode ID and uniquifier. Link: https://lore.kernel.org/r/3340431.1729680010@warthog.procyon.org.uk Fixes: 63a4681ff39c ("afs: Locally edit directory data for mkdir/create/unlink/...") cc: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Signed-off-by: David Howells Signed-off-by: Christian Brauner --- fs/afs/dir.c | 25 +++++++++++ fs/afs/dir_edit.c | 91 +++++++++++++++++++++++++++++++++++++- fs/afs/internal.h | 2 + include/trace/events/afs.h | 7 ++- 4 files changed, 122 insertions(+), 3 deletions(-) diff --git a/fs/afs/dir.c b/fs/afs/dir.c index f8622ed72e08..ada363af5aab 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include "internal.h" #include "afs_fs.h" @@ -1823,6 +1824,8 @@ error: static void afs_rename_success(struct afs_operation *op) { + struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry)); + _enter("op=%08x", op->debug_id); op->ctime = op->file[0].scb.status.mtime_client; @@ -1832,6 +1835,22 @@ static void afs_rename_success(struct afs_operation *op) op->ctime = op->file[1].scb.status.mtime_client; afs_vnode_commit_status(op, &op->file[1]); } + + /* If we're moving a subdir between dirs, we need to update + * its DV counter too as the ".." will be altered. + */ + if (S_ISDIR(vnode->netfs.inode.i_mode) && + op->file[0].vnode != op->file[1].vnode) { + u64 new_dv; + + write_seqlock(&vnode->cb_lock); + + new_dv = vnode->status.data_version + 1; + vnode->status.data_version = new_dv; + inode_set_iversion_raw(&vnode->netfs.inode, new_dv); + + write_sequnlock(&vnode->cb_lock); + } } static void afs_rename_edit_dir(struct afs_operation *op) @@ -1873,6 +1892,12 @@ static void afs_rename_edit_dir(struct afs_operation *op) &vnode->fid, afs_edit_dir_for_rename_2); } + if (S_ISDIR(vnode->netfs.inode.i_mode) && + new_dvnode != orig_dvnode && + test_bit(AFS_VNODE_DIR_VALID, &vnode->flags)) + afs_edit_dir_update_dotdot(vnode, new_dvnode, + afs_edit_dir_for_rename_sub); + new_inode = d_inode(new_dentry); if (new_inode) { spin_lock(&new_inode->i_lock); diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c index a71bff10496b..fe223fb78111 100644 --- a/fs/afs/dir_edit.c +++ b/fs/afs/dir_edit.c @@ -127,10 +127,10 @@ static struct folio *afs_dir_get_folio(struct afs_vnode *vnode, pgoff_t index) /* * Scan a directory block looking for a dirent of the right name. */ -static int afs_dir_scan_block(union afs_xdr_dir_block *block, struct qstr *name, +static int afs_dir_scan_block(const union afs_xdr_dir_block *block, const struct qstr *name, unsigned int blocknum) { - union afs_xdr_dirent *de; + const union afs_xdr_dirent *de; u64 bitmap; int d, len, n; @@ -492,3 +492,90 @@ error: clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); goto out_unmap; } + +/* + * Edit a subdirectory that has been moved between directories to update the + * ".." entry. + */ +void afs_edit_dir_update_dotdot(struct afs_vnode *vnode, struct afs_vnode *new_dvnode, + enum afs_edit_dir_reason why) +{ + union afs_xdr_dir_block *block; + union afs_xdr_dirent *de; + struct folio *folio; + unsigned int nr_blocks, b; + pgoff_t index; + loff_t i_size; + int slot; + + _enter(""); + + i_size = i_size_read(&vnode->netfs.inode); + if (i_size < AFS_DIR_BLOCK_SIZE) { + clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); + return; + } + nr_blocks = i_size / AFS_DIR_BLOCK_SIZE; + + /* Find a block that has sufficient slots available. Each folio + * contains two or more directory blocks. + */ + for (b = 0; b < nr_blocks; b++) { + index = b / AFS_DIR_BLOCKS_PER_PAGE; + folio = afs_dir_get_folio(vnode, index); + if (!folio) + goto error; + + block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_pos(folio)); + + /* Abandon the edit if we got a callback break. */ + if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags)) + goto invalidated; + + slot = afs_dir_scan_block(block, &dotdot_name, b); + if (slot >= 0) + goto found_dirent; + + kunmap_local(block); + folio_unlock(folio); + folio_put(folio); + } + + /* Didn't find the dirent to clobber. Download the directory again. */ + trace_afs_edit_dir(vnode, why, afs_edit_dir_update_nodd, + 0, 0, 0, 0, ".."); + clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); + goto out; + +found_dirent: + de = &block->dirents[slot]; + de->u.vnode = htonl(new_dvnode->fid.vnode); + de->u.unique = htonl(new_dvnode->fid.unique); + + trace_afs_edit_dir(vnode, why, afs_edit_dir_update_dd, b, slot, + ntohl(de->u.vnode), ntohl(de->u.unique), ".."); + + kunmap_local(block); + folio_unlock(folio); + folio_put(folio); + inode_set_iversion_raw(&vnode->netfs.inode, vnode->status.data_version); + +out: + _leave(""); + return; + +invalidated: + kunmap_local(block); + folio_unlock(folio); + folio_put(folio); + trace_afs_edit_dir(vnode, why, afs_edit_dir_update_inval, + 0, 0, 0, 0, ".."); + clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); + goto out; + +error: + trace_afs_edit_dir(vnode, why, afs_edit_dir_update_error, + 0, 0, 0, 0, ".."); + clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); + goto out; +} diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 6e1d3c4daf72..b306c0980870 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -1072,6 +1072,8 @@ extern void afs_check_for_remote_deletion(struct afs_operation *); extern void afs_edit_dir_add(struct afs_vnode *, struct qstr *, struct afs_fid *, enum afs_edit_dir_reason); extern void afs_edit_dir_remove(struct afs_vnode *, struct qstr *, enum afs_edit_dir_reason); +void afs_edit_dir_update_dotdot(struct afs_vnode *vnode, struct afs_vnode *new_dvnode, + enum afs_edit_dir_reason why); /* * dir_silly.c diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h index 450c44c83a5d..a0aed1a428a1 100644 --- a/include/trace/events/afs.h +++ b/include/trace/events/afs.h @@ -331,7 +331,11 @@ enum yfs_cm_operation { EM(afs_edit_dir_delete, "delete") \ EM(afs_edit_dir_delete_error, "d_err ") \ EM(afs_edit_dir_delete_inval, "d_invl") \ - E_(afs_edit_dir_delete_noent, "d_nent") + EM(afs_edit_dir_delete_noent, "d_nent") \ + EM(afs_edit_dir_update_dd, "u_ddot") \ + EM(afs_edit_dir_update_error, "u_fail") \ + EM(afs_edit_dir_update_inval, "u_invl") \ + E_(afs_edit_dir_update_nodd, "u_nodd") #define afs_edit_dir_reasons \ EM(afs_edit_dir_for_create, "Create") \ @@ -340,6 +344,7 @@ enum yfs_cm_operation { EM(afs_edit_dir_for_rename_0, "Renam0") \ EM(afs_edit_dir_for_rename_1, "Renam1") \ EM(afs_edit_dir_for_rename_2, "Renam2") \ + EM(afs_edit_dir_for_rename_sub, "RnmSub") \ EM(afs_edit_dir_for_rmdir, "RmDir ") \ EM(afs_edit_dir_for_silly_0, "S_Ren0") \ EM(afs_edit_dir_for_silly_1, "S_Ren1") \ From e65a0dc1cabe71b91ef5603e5814359451b74ca7 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 23 Oct 2024 11:07:05 +0100 Subject: [PATCH 5/7] iov_iter: Fix iov_iter_get_pages*() for folio_queue p9_get_mapped_pages() uses iov_iter_get_pages_alloc2() to extract pages from an iterator when performing a zero-copy request and under some circumstances, this crashes with odd page errors[1], for example, I see: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xbcf0 flags: 0x2000000000000000(zone=1) ... page dumped because: VM_BUG_ON_FOLIO(((unsigned int) folio_ref_count(folio) + 127u <= 127u)) ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:1444! This is because, unlike in iov_iter_extract_folioq_pages(), the iter_folioq_get_pages() helper function doesn't skip the current folio when iov_offset points to the end of it, but rather extracts the next page beyond the end of the folio and adds it to the list. Reading will then clobber the contents of this page, leading to system corruption, and if the page is not in use, put_page() may try to clean up the unused page. This can be worked around by copying the iterator before each extraction[2] and using iov_iter_advance() on the original as the advance function steps over the page we're at the end of. Fix this by skipping the page extraction if we're at the end of the folio. This was reproduced in the ktest environment[3] by forcing 9p to use the fscache caching mode and then reading a file through 9p. Fixes: db0aa2e9566f ("mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of folios") Reported-by: Antony Antony Closes: https://lore.kernel.org/r/ZxFQw4OI9rrc7UYc@Antony2201.local/ Signed-off-by: David Howells cc: Eric Van Hensbergen cc: Latchesar Ionkov cc: Dominique Martinet cc: Christian Schoenebeck cc: v9fs@lists.linux.dev cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/ZxFEi1Tod43pD6JC@moon.secunet.de/ [1] Link: https://lore.kernel.org/r/2299159.1729543103@warthog.procyon.org.uk/ [2] Link: https://github.com/koverstreet/ktest.git [3] Tested-by: Antony Antony Link: https://lore.kernel.org/r/3327438.1729678025@warthog.procyon.org.uk Signed-off-by: Christian Brauner --- lib/iov_iter.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 1abb32c0da50..cc4b5541eef8 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1021,15 +1021,18 @@ static ssize_t iter_folioq_get_pages(struct iov_iter *iter, size_t offset = iov_offset, fsize = folioq_folio_size(folioq, slot); size_t part = PAGE_SIZE - offset % PAGE_SIZE; - part = umin(part, umin(maxsize - extracted, fsize - offset)); - count -= part; - iov_offset += part; - extracted += part; + if (offset < fsize) { + part = umin(part, umin(maxsize - extracted, fsize - offset)); + count -= part; + iov_offset += part; + extracted += part; + + *pages = folio_page(folio, offset / PAGE_SIZE); + get_page(*pages); + pages++; + maxpages--; + } - *pages = folio_page(folio, offset / PAGE_SIZE); - get_page(*pages); - pages++; - maxpages--; if (maxpages == 0 || extracted >= maxsize) break; From f19910006effbd08398de79ca0233ea7e480616a Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Mon, 28 Oct 2024 06:47:17 +0800 Subject: [PATCH 6/7] autofs: fix thinko in validate_dev_ioctl() I was so sure the per-dentry expire timeout patch worked ok but my testing was flawed. In validate_dev_ioctl() the check for ioctl AUTOFS_DEV_IOCTL_TIMEOUT_CMD should use the ioctl number not the passed in ioctl command. Fixes: 433f9d76a010 ("autofs: add per dentry expire timeout") Cc: # mainline only Signed-off-by: Ian Kent Link: https://lore.kernel.org/r/20241027224732.5507-1-raven@themaw.net Signed-off-by: Christian Brauner --- fs/autofs/dev-ioctl.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/fs/autofs/dev-ioctl.c b/fs/autofs/dev-ioctl.c index f011e026358e..6d57efbb8110 100644 --- a/fs/autofs/dev-ioctl.c +++ b/fs/autofs/dev-ioctl.c @@ -110,6 +110,7 @@ static inline void free_dev_ioctl(struct autofs_dev_ioctl *param) */ static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param) { + unsigned int inr = _IOC_NR(cmd); int err; err = check_dev_ioctl_version(cmd, param); @@ -133,7 +134,7 @@ static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param) * check_name() return for AUTOFS_DEV_IOCTL_TIMEOUT_CMD. */ err = check_name(param->path); - if (cmd == AUTOFS_DEV_IOCTL_TIMEOUT_CMD) + if (inr == AUTOFS_DEV_IOCTL_TIMEOUT_CMD) err = err ? 0 : -EINVAL; if (err) { pr_warn("invalid path supplied for cmd(0x%08x)\n", @@ -141,8 +142,6 @@ static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param) goto out; } } else { - unsigned int inr = _IOC_NR(cmd); - if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD || inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD || inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) { From c749d9b7ebbc5716af7a95f7768634b30d9446ec Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sun, 27 Oct 2024 15:23:23 -0700 Subject: [PATCH 7/7] iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP generic/077 on x86_32 CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y with highmem, on huge=always tmpfs, issues a warning and then hangs (interruptibly): WARNING: CPU: 5 PID: 3517 at mm/highmem.c:622 kunmap_local_indexed+0x62/0xc9 CPU: 5 UID: 0 PID: 3517 Comm: cp Not tainted 6.12.0-rc4 #2 ... copy_page_from_iter_atomic+0xa6/0x5ec generic_perform_write+0xf6/0x1b4 shmem_file_write_iter+0x54/0x67 Fix copy_page_from_iter_atomic() by limiting it in that case (include/linux/skbuff.h skb_frag_must_loop() does similar). But going forward, perhaps CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is too surprising, has outlived its usefulness, and should just be removed? Fixes: 908a1ad89466 ("iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic()") Signed-off-by: Hugh Dickins Link: https://lore.kernel.org/r/dd5f0c89-186e-18e1-4f43-19a60f5a9774@google.com Reviewed-by: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner --- lib/iov_iter.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index cc4b5541eef8..908e75a28d90 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -461,6 +461,8 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, size_t bytes, struct iov_iter *i) { size_t n, copied = 0; + bool uses_kmap = IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) || + PageHighMem(page); if (!page_copy_sane(page, offset, bytes)) return 0; @@ -471,7 +473,7 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, char *p; n = bytes - copied; - if (PageHighMem(page)) { + if (uses_kmap) { page += offset / PAGE_SIZE; offset %= PAGE_SIZE; n = min_t(size_t, n, PAGE_SIZE - offset); @@ -482,7 +484,7 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, kunmap_atomic(p); copied += n; offset += n; - } while (PageHighMem(page) && copied != bytes && n > 0); + } while (uses_kmap && copied != bytes && n > 0); return copied; }