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ext4: support uncached buffered I/O

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Set FOP_DONTCACHE in ext4_file_operations to declare support for
uncached buffered I/O.

To handle this flag, update ext4_write_begin() and ext4_da_write_begin()
to use write_begin_get_folio(), which encapsulates FGP_DONTCACHE logic
based on iocb->ki_flags.

Part of a series refactoring address_space_operations write_begin and
write_end callbacks to use struct kiocb for passing write context and
flags.

Signed-off-by: Taotao Chen <chentaotao@didiglobal.com>
Link: https://lore.kernel.org/20250716093559.217344-6-chentaotao@didiglobal.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Taotao Chen
2025-07-16 09:36:09 +00:00
committed by Christian Brauner
parent b799474b9a
commit ae21c0c0ac
2 changed files with 5 additions and 10 deletions
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12
fs/ext4/inode.c
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@@ -1264,7 +1264,6 @@ static int ext4_write_begin(const struct kiocb *iocb,
struct folio *folio;
pgoff_t index;
unsigned from, to;
fgf_t fgp = FGP_WRITEBEGIN;
ret = ext4_emergency_state(inode->i_sb);
if (unlikely(ret))
@@ -1288,16 +1287,14 @@ static int ext4_write_begin(const struct kiocb *iocb,
}
/*
* __filemap_get_folio() can take a long time if the
* write_begin_get_folio() can take a long time if the
* system is thrashing due to memory pressure, or if the folio
* is being written back. So grab it first before we start
* the transaction handle. This also allows us to allocate
* the folio (if needed) without using GFP_NOFS.
*/
retry_grab:
fgp |= fgf_set_order(len);
folio = __filemap_get_folio(mapping, index, fgp,
mapping_gfp_mask(mapping));
folio = write_begin_get_folio(iocb, mapping, index, len);
if (IS_ERR(folio))
return PTR_ERR(folio);
@@ -3046,7 +3043,6 @@ static int ext4_da_write_begin(const struct kiocb *iocb,
struct folio *folio;
pgoff_t index;
struct inode *inode = mapping->host;
fgf_t fgp = FGP_WRITEBEGIN;
ret = ext4_emergency_state(inode->i_sb);
if (unlikely(ret))
@@ -3072,9 +3068,7 @@ static int ext4_da_write_begin(const struct kiocb *iocb,
}
retry:
fgp |= fgf_set_order(len);
folio = __filemap_get_folio(mapping, index, fgp,
mapping_gfp_mask(mapping));
folio = write_begin_get_folio(iocb, mapping, index, len);
if (IS_ERR(folio))
return PTR_ERR(folio);